Saturday, April 9, 2016

Is Planet X Linked to Mass Extinctions?

Is Planet X Linked to Mass Extinctions?:



This artwork shows a rocky planet being bombarded by comets. Image credit: NASA/JPL-Caltech


Planet Nine, the massive orb proposed to explain the clustered orbits of a half dozen remote Kuiper Belt asteroids, may have a darker side. Periodic mass extinctions on Earth, as indicated in the global fossil record, could be linked to the hypothetical planet according to research published by Daniel Whitmire, a retired professor of astrophysics and faculty member of the University of Arkansas Department of Mathematical Sciences.Planet Nine is estimated to be 10 times more massive than Earth and currently orbiting about 1,000 times farther away from the Sun. Astronomers have been searching for a potential large planet — for years called "Planet X" — that might be implicated in a handful of major mass extinctions over the past 500 million years. During those times, between 50 and more than 90% of species on Earth perished in a geological heartbeat. The worst, dubbed the Permian-Triassic event or the Great Dying, occurred 250 million years ago and saw the disappearance of more than 90% of the planet's life in a geological heartbeat.Whitmire and his colleague, John Matese, first published research on the connection between Planet X and mass extinctions in the journal Nature in 1985 while working as astrophysicists at the University of Louisiana at Lafayette. They proposed that perturbations from a 10th planet (Pluto was considered a planet back then) could fling a shower of comets from the Kuiper Belt beyond Neptune in Earth's direction every 28 million years in sync with recorded mass extinctions.Two other ideas also proposed at the time they wrote their paper — a sister star to the Sun and vertical oscillations of the Sun as it orbits the galaxy — have since been ruled out because the timing is inconsistent with the extinction record. Only Planet X remained as a viable theory, and it's now gaining renewed attention.https://www.youtube.com/watch?v=hSXNE0pNtr8 Neil deGrasse Tyson explains precession and Mercury's orbitWhitmire and Matese proposed that as Planet X orbits the Sun, its tilted orbit slowly rotates, causing the location of its perihelion (closest point to the Sun) to slowly precess or shift position along its orbit instead of remaining in the same place. Every planet precesses, so no surprises here.But location can make a huge difference. The team proposed that Planet X's slow orbital gyration directs it into the Kuiper Belt approximately every 27 million years, knocking comets into the inner Solar System. The dislodged comets not only smash into the Earth, they also vaporize and break apart in the inner Solar System as they get nearer to the Sun, reducing the amount of sunlight that reaches the Earth. Add it up, and you have a recipe for cyclic destruction.One thing to keep in mind is that their research led them to conclude that Planet X was only 5 times as massive as Earth and 100 times farther from the Sun. This doesn't jive with the size and mass particulars for Planet Nine inferred by researchers Konstantin Batygin and Michael E. Brown at Caltech earlier this year, but until someone tracks the real planet down, there's room for argument.Comet and asteroid showers are often cited as possible bad guys in extinction episodes. And why not? We have hard evidence of the asteroid impact that sealed the dinosaurs's fate 65 million years ago and have seen some six impacts at Jupiter since 1994. It's cosmic billiards out there folks, and the game's not over.

The post Is Planet X Linked to Mass Extinctions? appeared first on Universe Today.

Posted by Nelio Inacio at 12:20 PM 0 comments

Ten Interesting Facts About Jupiter

Ten Interesting Facts About Jupiter:



Jupiter's Red Spot, seen by Voyager 1. Image credit: NASA/JPL


Jupiter was appropriately named after the king of the gods. It's massive, has a powerful magnetic field, and more moons that any planet in the Solar System. Though it has been known to astronomers since ancient times, the invention of the telescope and the advent of modern astronomy has taught us so much about this gas giant.In short, there are countless interesting facts about this gas giant that many people just don't know about. And we here at Universe Today have taken the liberty of compiling a list of ten particularly interesting ones that we think will fascinate and surprise you. Think you know everything about Jupiter? Think again!

1. Jupiter Is Massive:

It's no secret that Jupiter is the largest planet in the Solar System. But this description really doesn't do it justice. For one, the mass of Jupiter is 318 times as massive as the Earth. In fact, Jupiter is 2.5 times more massive than all of the other planets in the Solar System combined. But here's the really interesting thing...If Jupiter got any more massive, it would actually get smaller. Additional mass would actually make the planet more dense, which would cause it to start pulling it in on itself. Astronomers estimate that Jupiter could end up with 4 times its current mass, and still remain about the same size.

2. Jupiter Cannot Become A Star:

Astronomers call Jupiter a failed star, but that's not really an appropriate description. While it is true that, like a star, Jupiter is rich in hydrogen and helium, Jupiter does not have nearly enough mass to trigger a fusion reaction in its core. This is how stars generate energy, by fusing hydrogen atoms together under extreme heat and pressure to create helium, releasing light and heat in the process.This is made possible by their enormous gravity. For Jupiter to ignite a nuclear fusion process and become a star, it would need more than 70 times its current mass. If you could crash dozens of Jupiters together, you might have a chance to make a new star. But in the meantime, Jupiter shall remain a large gas giant with no hopes of becoming a star. Sorry, Jupiter!https://youtu.be/v9HtCAHv54E

3. Jupiter Is The Fastest Spinning Planet In The Solar System:

For all its size and mass, Jupiter sure moves quickly. In fact, with an rotational velocity of 12.6 km/s (~7.45 m/s) or 45,300 km/h (28,148 mph), the planet only takes about 10 hours to complete a full rotation on its axis. And because it's spinning so rapidly, the planet has flattened out at the poles a little and is bulging at its equator.In fact, points on Jupiter's equator are more than 4,600 km further from the center than the poles. Or to put it another way, the planet's polar radius measures to 66,854 ± 10 km (or 10.517 that of Earth's), while its diameter at the equator is 71,492 ± 4 km (or 11.209 that of Earth's). This rapid rotation also helps generate Jupiter's powerful magnetic fields, and contribute to the dangerous radiation surrounding it.

4. The Clouds On Jupiter Are Only 50 km Thick:

That's right, all those beautiful whirling clouds and storms you see on Jupiter are only about 50 km thick. They're made of ammonia crystals broken up into two different cloud decks. The darker material is thought to be compounds brought up from deeper inside Jupiter, and then change color when they reacted with sunlight. But below those clouds, it's just hydrogen and helium, all the way down.

5. The Great Red Spot Has Been Around For A Long Time:

The Great Red Spot on Jupiter is one of its most familiar features. This persistent anticyclonic storm, which is located south of its equator, measures between 24,000 km in diameter and 12–14,000 km in height. As such, it is large enough to contain two or three planets the size of Earth's diameter. And the spot has been around for at least 350 years, since it was spotted as far back as the 17th century.The Great Red Spot was first identified in 1665 by Italian astronomer Giovanni Cassini. By the 20th century, astronomers began to theorize that it was a storm, one which was created by Jupiter's turbulent and fast-moving atmosphere. These theories were confirmed by the Voyager 1 mission, which observed the Giant Red Spot up close in March of 1979 during its flyby of the planet.However, it appears to have been shrinking since that time. Based on Cassini's observations, the size was estimated to be 40,000 km in the 17th century, which was almost twice as large as it is now. Astronomers do not know if or when it will ever disappear entirely, but they are relatively sure that another one will emerge somewhere else on the planet.

6. Jupiter Has Rings:

When people think of ring systems, Saturn naturally comes to mind. But in truth, both Uranus and Jupiter have ring systems of their own. Jupiter's were the third set to be discovered (after the other two), due to the fact that they are particularly faint. Jupiter's rings consist of three main segments - an inner torus of particles known as the halo, a relatively bright main ring, and an outer gossamer ring.These rings are widely believed to have come from material ejected by its moons when they're struck by meteorite impacts. In particular, the main ring is thought to be composed of material from the moons of Adrastea and Metis, while the moons of Thebe and Amalthea are believed to produce the two distinct components of the dusty gossamer ring.This material fell into orbit around Jupiter (instead of falling back to their respective moons) because if Jupiter's strong gravitational influence. The ring is also depleted and replenished regularly as some material veers towards Jupiter while new material is added by additional impacts.

7. Jupiter's Magnetic Field Is 14 Times Stronger Than Earth's:

Compasses would really work on Jupiter. That's because it has the strongest magnetic field in the Solar System. Astronomers think the magnetic field is generated by the eddy currents - i.e. swirling movements of conducting materials - within the liquid metallic hydrogen core. This magnetic field traps particles of sulfur dioxide from Io's volcanic eruptions, which producing sulfur and oxygen ions. Together with hydrogen ions originating from the atmosphere of Jupiter, these form a plasma sheet in Jupiter's equatorial plane.Farther out, the interaction of the magnetosphere with the solar wind generates a bow shock, a dangerous belt of radiation that can cause damage tos spacecraft. Jupiter's four largest moons all orbit within the magnetosphere, which protects them from the solar wind, but also make the likelihood of establishing outposts on their surface problematic. The magnetosphere of Jupiter is also responsible for intense episodes of radio emission from the planet's polar regions.

8. Jupiter Has 67 Moons:

As of the penning of this article, Jupiter has a 67 confirmed and named satellites. However, it is estimated that the planet has over 200 natural satellites orbiting it. Almost all of them are less than 10 kilometers in diameter, and were only discovered after 1975, when the first spacecraft (Pioneer 10) arrived at Jupiter.However, it also has four major moons, which are collectively known as the Galilean Moons (after their discovered Galileo Galilei). These are, in order of distance from Jupiter, Io, Europa, Ganymede, and Callisto. These moons are some of the largest in the Solar System, with Ganymede being the largest, measuring 5262 km in diameter.

9. Jupiter Has Been Visited 7 Times By Spacecraft:

Jupiter was first visited by NASA's Pioneer 10 spacecraft in December 1973, and then Pioneer 11 in December 1974. Then came the Voyager 1 and 2 flybys, both of which happened in 1979. This was followed by a long break until Ulysses arrived in February 1992, followed by the Galileo space probe in 1995. Then Cassini made a flyby in 2000, on its way to Saturn. And finally, NASA's New Horizons spacecraft made its flyby in 2007. This was the last mission to fly past Jupiter, but it surely won't be the last.

10. You Can See Jupiter With Your Own Eyes:

Jupiter is the third brightest object in the Solar System, after Venus and the Moon. Chances are, you saw Jupiter in the sky, and had no idea that's what you were seeing. And here at Universe Today, we are in the habit of letting readers know when the best opportunities for spotting Jupiter in the night sky are.Chances are, if you see a really bright star high in the sky, then you're looking at Jupiter. Get your hands on a pair of binoculars, and if you know someone with a telescope, that's even better. Using even modest magnification, you might even spot small specks of light orbiting it, which are its Galilean Moons. Just think, you'll be seeing precisely what Galileo did when he gazed at the planet in 1610.We have written many interesting articles about Jupiter here at Universe Today. Here's The Gas Giant Jupiter, How Strong Is Jupiter's Gravity?, Does Jupiter Have A Solid Core?, and Jupiter Compared To Earth.And here are 10 Interesting Facts About Planet Earth, and 1o Interesting Facts About Mars.For more information, check out the Hubblesite's News Releases about Jupiter, and NASA's Solar System Exploration.We've also recorded an entire show just on Jupiter for Astronomy Cast. Listen to it here, Episode 56: Jupiter, and Episode 57: Jupiter's Moons.

The post Ten Interesting Facts About Jupiter appeared first on Universe Today.

Posted by Nelio Inacio at 12:19 PM 0 comments

Huygens Spots Methane Fog On Saturn’s Moon Titan

Huygens Spots Methane Fog On Saturn’s Moon Titan:



Titan's dense, hydrocarbon rich atmosphere remains a focal point of scientific research. Credit: NASA


Titan is a moon shrouded in mystery. Despite multiple flybys and surface exploration conducted in the past few decades, this Cronian moon still manages to surprise us from time to time. In addition to having a dense atmosphere rich in hydrocarbons, which scientists believe may be similar to what Earth's own atmosphere was like billions of years ago, it appears that methane is to Titan what water is to planet Earth.In addition, methane fog was also observed by the Cassini space probe back in 2009 as it conducted a flyby of Titan. But recent findings by a team of researchers from York University indicates that the Huygens lander also detected fog during its descent towards the surface in 2005. This evidence, combined with the data obtained by Cassini, have helped to shed light on the weather patterns of this mysterious moon.In a paper that appeared in arXiv on March 14th, Dr. Christina Smith - a postdoctoral researcher from York University's Center for Research in Earth and Space Sciences (CRESS) - described how the Huygens probe's Side Looking Imager (SLI) obtained information that has since been analyzed to identify potential atmospheric features. These features show that Titan experiences meteorological phenomena which were not previously known.In total, the team looked over 82 SLI images, which were all taken after the lander reached the surface. These were then calibrated, processed and examined for signs of atmospheric features. Of these, six showed evidence of an extended horizontal feature that differed in radiance from what was predicted at higher and lower regions. No other discernible features were detected.The team concluded that this feature most likely originated from the presence of a fog bank close to the horizon that rose and fell during the period of observation. This indicated that it had recently rained in the area, which was a rather surprising find. Much like the observations made in 2009, the presence of methane fog shows that Titan has an active methane hydrological cycle.In essence, this means that methane on Titan is subject to the same transfer process as water is here on Earth. Basically, liquid methane on the surface evaporates and is exchanged with the atmosphere, where it condenses to form fog banks and rain clouds. As Christina Smith told Universe Today via email:

"We initially set out to see if we could see features such as clouds from the Huygens SLI data, but the features we found don't seem to be consistent with clouds and more likely are caused by a fog bank rising and falling over the time of observation. Fog had been seen before from orbit but never from the surface of Titan - this is what makes this work so exciting. This work is also a great example of how new insights and new findings can be made from "older" data sets."
Looking over this old data for the sake of making new discoveries was made possible, in part, because of the ongoing investigations conducted by Martian rovers and their respective science teams. Brittney Cooper - an undergraduate research assistant at CRESS and the second author of the paper - explained via email:

"We applied a technique of image analysis developed by Mark Lemmon for use with the Mars Exploration Rovers that was adapted by John Moores for use on the Mars Phoenix lander mission. This analysis method allowed the faint, barely observable atmospheric features captured by the Huygens' probe Side Looking Imager (SLI) on Titan to be amplified and more easily discerned."
For years, scientists have understood that on Titan, methane is analogous to water. It exists in liquid form (especially around the north pole where several large methane lakes exist), and in gaseous form in the atmosphere. However, what they did not know was whether or not there was an active cycle, where liquid methane on the surface was replenished through evaporation, condensation, and rain.But this evidence, combined with the Cassini probe data, shows that on Titan, there is an active transfer process between the liquid methane and the atmospheric methane. And where atmospheric humidity reaches 100%, methane fogs will form. Just the latest in a long line of fascinating discoveries to emerge from this mysterious moon!

Further Reading: arXiv.com
The post Huygens Spots Methane Fog On Saturn’s Moon Titan appeared first on Universe Today.

Posted by Nelio Inacio at 12:17 PM 0 comments

GRAIL Data Points To Possible Lava Tubes On The Moon

GRAIL Data Points To Possible Lava Tubes On The Moon:



Map showing variations in the lunar gravity field, as measured by NASA's Gravity Recovery and Interior Laboratory (GRAIL) . Credit: NASA/JPL-Caltech/MIT/GSFC


For years, scientists have been hunting for the stable lava tubes that are believed to exist on the Moon. A remnant from the Moon's past, when it was still volcanically active, these underground channels could very well be an ideal location for lunar colonies someday. Not only would their thick roofs provide naturally shielding from solar radiation, meteoric impacts, and extremes in temperature. They could also be pressurized to create a breathable environment.But until now, evidence of their existence has been inferred from surface features such as sinuous rilles - channel-like depressions that run along the surface that indicate the presence of subterranean lava flows - and holes in the surface (aka. "skylights"). However, recent evidence presented at the 47th Lunar and Planetary Science Conference (LPSC) in Texas indicates that one such stable lava tube could exist in the once-active region known as Marius Hills.

The presentation was led by Rohan Sood, a graduate research assistant from the department of Aeronautics and Astronautics at Purdue University in Indiana. For some time now, Sood and his research colleagues have been examining data obtained from NASA's twin Gravity Recovery and Interior Laboratory (GRAIL) mission in order to get a better sense of what the Moon's interior looks like.

Launched in 2011, the purpose of the GRAIL mission - which consists of two orbiters, Ebb and Flow, working in tandem - was to map the Moon's gravity with extreme precision. Over time, the information it gathered has provided scientists with the opportunity to gain a better understanding of the Moon's subsurface features, particularly the buried lava tubes that are believed to exist.

In 2009, the Japan Aerospace Exploration Agency's (JAXA) Kaguya spacecraft (aka. Selene) confirmed the presence of a skylight in the Marius Hills region, which has since come to be known as the "Marius Hole". In 2011, it was photographed in more detail by the Lunar Reconnaissance Orbiter, which showed that it was approximately 65 meters wide and 80 meters deep. The fact that this hole sat between two rilles indicated that it was evidence that lava once flowed beneath the region.Using the GRAIL gravity data that was collected at different altitudes, the Purdue team went about assessing the presence and extent of ancient lava tubes beneath the surface of Marius Hills. What they determined was rather interesting. As Sood told Universe Today via email:

"Thanks to NASA's GRAIL mission, we now have derived the lunar gravity field to an unprecedented resolution and accuracy. The data allows us to dig below the lunar surface, with our objective being to recognize signatures that may correspond to those of empty lava tubes."
To assess the possibility of lava tubes, Sood and his team relied on a two-tiered strategy of gradiometry and cross-correlationon specific regions. Whereas gradiometry calculates the gravitational potential from a spherical harmonics data set, cross-correlation utilizes the individual track data based on the relative acceleration between the two spacecraft as they move along their respective orbits.Much like Earth, the moon’s gravitational field is affected by masses below the surface. "Any gravitational field is affected by the density of material," said Sood. "If you are flying the spacecraft over a block of dense material, it will experience an increase in gravitational pull in contrary to flying over a lava tube void, in which case there will be a decrease in gravitational attraction experienced by the spacecraft."Where the Marius Hole is located, the team spotted a gravitational signature that was indicative of a subsurface cavity. But that was not all. Distributed across the Moon's near side, Sood and his colleagues also noted that the GRAIL data indicated at least ten signatures that could resemble lava tubes. All are located near the dark areas left by ancient volcanic seas, with some measuring more than 100 km long and several kilometers wide.Naturally, there are some doubts as to whether or not the readings are indicative of actual lava tubes. As the team indicated in their paper - "Detection of Buried Empty Lunar Lava Tubes Using Grail Gravity Data", which contains the findings they presented at the 47th Lunar and Planetary Science Conference - the structures they were looking for were similar or smaller in scale than the resolution of the gravity data.As a result, it was difficult to determine whether or not the signals they spotted were in fact a sign of an underground recess, or a numerical artifact in the data. Because of this, proving the existence of stable, subsurface lava tubes will require a next-generation mission, one that has instruments which will be able to penetrate the lunar surface and confirm the presence of recesses."[W]e have to remember that gravity is non-unique," Sood added, "which means, in order to support our findings and to add to our ongoing efforts, our team is considering a ground penetrating radar that will probe the lunar subsurface from orbit. The goal of the radar would be to confirm the presence of the potential lava tube candidates that we have detected so far, and in addition, look for smaller lava tubes that were beyond the resolution of GRAIL gravity data."One possibility is a concept Sood and his colleagues have proposed themselves - the Lunar Advanced Radar Orbiter For Subsurface Sounding (LAROSS) mission. Designed to build upon the success of the GRAIL mission, the concept calls for a spacecraft equipped with ground-penetrating radar to conduct a sounding mission that would potentially confirm both the presence and size of the Moon's buried empty lava tubes.This is not the first time that researchers from Purdue have presented a case for stable lunar lava tubes at the Lunar and Planetary Science Conference. Last year, at the 46th annual conference, a research team from the Department of Earth, Atmospheric and Planetary Sciences (which included Sood) used data similarly provided by the GRAIL mission to determine that some lunar lava tubes could measure up to 1 km in width.These latest findings, which not only produced more evidence of such subsurface spaces, but indicated that they may be even larger than previously expected, is good news for advocates of lunar settlement. It is also worth noting that since it began surveying the moon, the Lunar Reconnaissance Orbiter has imaged over 200 pits that show signs of being skylights.Each of these holes could lead to subsurface voids or caverns, which range in diameter from about 16 feet (5 meters) to more than 2,950 feet (900 m). Assuming that just a fraction of these lead to underground tubes that are large enough to house an entire Earth city, there would be no shortage of possible settlement sites if and when it comes time to colonize the Moon.After all, one of the biggest challenges in settling on a body where there is no atmosphere to speak of is creating a sturdy and airtight protective shelter. Another major challenge is shielding the occupants of these and other shelters from incoming cosmic rays and solar radiation since their is no ozone layer to filter them out.Where better than in an underground tunnel that will not only shield inhabitants from harmful radiation, meteoric impacts, and extremes in temperature, but also has immensely thick walls to keep the air in? In all likelihood, if and when there is such a thing as "Lunies", they will dwell in elongated caverns beneath the Moon's surface.Further Reading: Universities Space Research Assocation

The post GRAIL Data Points To Possible Lava Tubes On The Moon appeared first on Universe Today.

Posted by Nelio Inacio at 12:17 PM 0 comments

How Long Does It Take to Get to Jupiter?

How Long Does It Take to Get to Jupiter?:

We’re always talking about Pluto, or Saturn or Mars. But nobody ever seems to talk about Jupiter any more. Why is that? I mean, it’s the largest planet in the Solar System. 318 times the mass of the Earth has got to count for something, right? Right?

Jupiter with Io and Ganymede taken by amateur astronomer Damian Peach. Credit: NASA / Damian Peach

Jupiter with Io and Ganymede taken by amateur astronomer Damian Peach. Credit: NASA / Damian Peach
Jupiter is one of the most important places in the Solar System. The planet itself is impressive; with ancient cyclonic storms larger than the Earth, or a magnetosphere so powerful it defies comprehension.

One of the most compelling reasons to visit Jupiter is because of its moons. Europa, Callisto and Ganymede might all contain vast oceans of liquid water underneath icy shells. And as you probably know, wherever we find liquid water on Earth, we find life.

And so, the icy moons of Jupiter are probably the best place to look for life in the entire Solar System.

And yet, as I record this video in early 2016, there are no spacecraft at Jupiter or its moons. In fact, there haven’t been any there for years. The last spacecraft to visit Jupiter was NASA’s New Horizons in 2007. Mars is buzzing with orbiters and rovers, we just got close up pictures of Pluto! and yet we haven’t seen Jupiter close up in almost 10 years. What’s going on?

Part of the problem is that Jupiter is really far away, and it takes a long time to get there.

How long? Let’s take a look at all the spacecraft that have ever made this journey.

The first spacecraft to ever cross the gulf from the Earth to Jupiter was NASA’s Pioneer 10. It launched on March 3, 1972 and reached on December 3, 1973. That’s a total of 640 days of flight time.

But Pioneer 10 was just flying by, on its way to explore the outer Solar System. It came within 130,000 km of the planet, took the first close up pictures ever taken of Jupiter, and then continued on into deep space for another 11 years before NASA lost contact.

Pioneer 11 took off a year later, and arrived a year later. It made the journey in 606 days, making a much closer flyby, getting within 21,000 kilometers of Jupiter, and visiting Saturn too.

Next came the Voyager spacecraft. Voyager 1 took only 546 days, arriving on March 5, 1979, and Voyager 2 took 688 days.

So, if you’re going to do a flyby, you’ll need about 550-650 days to make the journey.

But if you actually want to slow down and go into orbit around Jupiter, you’ll need to take a much slower journey. The only spacecraft to ever stick around Jupiter was NASA’s Galileo spacecraft, which launched on October 18, 1989.

Instead of taking the direct path to Jupiter, it made two gravitational assisting flybys of Earth and one of Venus to pick up speed, finally arriving at Jupiter on December 8, 1995. That’s a total of 2,242 days.

So why did Galileo take so much longer to get to Jupiter? It’s because you need to be going slow enough that when you reach Jupiter, you can actually enter orbit around the planet, and not just speed on past.

And now, after this long period of Jupiterlessness, we’re about to have another spacecraft arrive at the massive planet and go into orbit. NASA’s Juno spacecraft was launched back on August 5, 2011 and it’s been buzzing around the inner Solar System, building up the velocity to make the journey to Jupiter.

NASA's Juno spacecraft launched on August 6, 2011 and should arrive at Jupiter on July 4, 2016. Credit: NASA / JPL

NASA’s Juno spacecraft launched on August 6, 2011 and should arrive at Jupiter on July 4, 2016. Credit: NASA / JPL
It did a flyby of Earth back in 2013, and if everything goes well, Juno will make its orbital insertion into the Jovian system on July 4, 2016. Total flight time: 1,795 days.

Once again, we’ll have a spacecraft observing Jupiter and its moon.s

This is just the beginning. There are several more missions to Jupiter in the works. The European Space Agency will be launching the Jupiter Icy Moons Mission in 2022, which will take nearly 8 years to reach Jupiter by 2030.

NASA’s Europa Multiple-Flyby Mission [Editor’s note: formerly known as the Europa Clipper] will probably launch in the same timeframe, and spend its time orbiting Europa, trying to get a better understand the environment on Europa. It probably won’t be able to detect any life down there, beneath the ice, but it’ll figure out exactly where the ocean starts.

So, how long does it take to get to Jupiter? Around 600 days if you want to just do a flyby and aren’t planning to stick around, or about 2,000 days if you want to actually get into orbit.

The post How Long Does It Take to Get to Jupiter? appeared first on Universe Today.

Posted by Nelio Inacio at 12:17 PM 0 comments

Mysterious Pull On Cassini Probe May Help Find Planet Nine

Mysterious Pull On Cassini Probe May Help Find Planet Nine:



Artist's impression of Planet Nine, blocking out the Milky Way. The Sun is in the distance, with the orbit of Neptune shown as a ring. Credit: ESO/Tomruen/nagualdesign


Finding a ninth planet in our Solar System this late in the game would be fascinating. It would also be somewhat of a surprise, considering our observational capabilities. But new evidence, in the form of small perturbations in the orbit of the Cassini probe, points to the existence of an as-yet undetected planet in our solar system.Back in January, Konstantin Batygin and Mike Brown, two planetary scientists from the California Institute of Technology, presented evidence supporting the existence of a ninth planet. Their paper showed that some Kuiper Belt Objects (KBOs) display unexpected behaviour. It appears that 6 KBOs are affected by their relationship to a large object, but the KBOs in question are too distant from the known gas giants for them to be responsible. They think that a large, distant planet, in the distant reaches of our Solar System, could be responsible for the unexpected orbital clustering of these KBOs.Now, the Ninth Planet idea is gaining steam, and another team of researchers have presented evidence that small perturbations in the orbit of the Cassini spacecraft are caused by the new planet. Agnès Fienga at the Côte d’Azur Observatory in France, and her colleagues, have been working on a detailed model of the Solar System for over a decade. They plugged the hypothetical orbit and size of Planet Nine into their model, to see if it fit.Planet Nine is calculated to be about 4 times as large as Earth, and 10 times as massive. It's orbit takes between 10,000 and 20,000 years. A planet that large can only be hiding in so many places, and those places are a long way from Earth. Fienga found a potential home for Planet Nine, some 600 astronomical units (AU) from here. That much mass at that location could account for the perturbations in Cassini's orbit.There's more good news when it comes to Planet Nine. By happy accident, it's predicted location in the sky is towards the constellation Cetus, in the southern hemisphere. This means that it is in the view of the Dark Energy Survey, a southern hemisphere project that is studying the acceleration of the universe. The Dark Energy Survey is not designed to search for planetary objects, but it has successfully found at least one icy object.There are other ways that the existence of Planet Nine could be confirmed. If it's as large as thought, then it will radiate enough internal heat to be detected by instruments designed to study the Cosmic Microwave Background (CMB). There is also an enormous amount of data from multiple experiments and observations done over the years that might contain an inadvertent clue. But looking through it is an enormous task.As for Brown and Batygin, who initially proposed the existence of Planet Nine based on the behaviour of KBOs, they are already proposing a more specific hunt for the elusive planet. They have asked for a substantial amount of observing time at the Subaru Telescope on Mauna Kea in Hawaii, in order to examine closely the location that Fienga's solar system model predicts Planet Nine to be at.For a more detailed look at Batygin's and Brown's work analyzing KBOs, read Matt Williams' article here.

The post Mysterious Pull On Cassini Probe May Help Find Planet Nine appeared first on Universe Today.

Posted by Nelio Inacio at 12:16 PM 0 comments

Nearby Supernovas Showered Earth With Iron

Nearby Supernovas Showered Earth With Iron:



Visible, infrared, and X-ray light image of Kepler's supernova remnant (SN 1604) located about 13,000 light-years away. Credit: NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University).


We all know that we are "made of star-stuff," with all of the elements necessary for the formation of planets and even life itself having originated inside generations of massive stars, which over billions of years have blasted their creations out into the galaxy at the explosive ends of their lives. Supernovas are some of the most powerful and energetic events in the known Universe, and when a dying star finally explodes you wouldn't want to be anywhere nearby—fresh elements are nice and all but the energy and radiation from a supernova would roast any planets within tens if not hundreds of light-years in all directions. Luckily for us we're not in an unsafe range of any supernovas in the foreseeable future, but there was a time geologically not very long ago that these stellar explosions are thought to have occurred in nearby space... and scientists have recently found the "smoking gun" evidence at the bottom of the ocean.Two independent teams of "deep-sea astronomers"—one led by Dieter Breitschwerdt from the Berlin Institute of Technology and the other by Anton Wallner from the Australian National University—have investigated sediment samples taken from the floors of the Pacific, Atlantic, and Indian oceans. The sediments were found to contain relatively high levels of iron-60, an unstable isotope specifically created during supernovas.Watch: How Quickly Does a Supernova Happen?The teams found that the ages of the iron-60 concentrations (the determination of which was recently perfected by Wallner) centered around two time periods, 1.7 to 3.2 million years ago and 6.5 to 8.7 million years ago. Based on this and the fact that our Solar System currently resides within a peanut-shaped region virtually empty of interstellar gas known as the Local Bubble, the researchers are confident that this provides further evidence that supernovas exploded within a mere 330 light-years of Earth, sending their elemental fallout our way.“This research essentially proves that certain events happened in the not-too-distant past," said Adrian Melott, an astrophysicist and professor at the University of Kansas who was not directly involved with the research but published his take on the findings in a letter in Nature. (Source)The researchers think that two supernova events in particular were responsible for nearly half of the iron-60 concentrations now observed. These are thought to have taken place among a a nearby group of stars known as the Scorpius–Centaurus Association, some 2.3 and 1.5 million years ago. At those same time frames Earth was entering a phase of repeated global glaciation, the end of the last of which led to the rise of modern human civilization.While supernovas of those sizes and distances wouldn't have been a direct danger to life here on Earth, could they have played a part in changing the climate?Read more: Could a Faraway Supernova Threaten Earth?“Our local research group is working on figuring out what the effects were likely to have been,” Melott said. “We really don’t know. The events weren’t close enough to cause a big mass extinction or severe effects, but not so far away that we can ignore them either. We’re trying to decide if we should expect to have seen any effects on the ground on the Earth.”Regardless of the correlation, if any, between ice ages and supernovas, it's important to learn how these events do affect Earth and realize that they may have played an important and perhaps overlooked role in the history of life on our planet."Over the past 500 million years there must have been supernovae very nearby with disastrous consequences," said Melott. "There have been a lot of mass extinctions, but at this point we don't have enough information to tease out the role of supernovae in them."You can find the teams' papers in Nature here and here.Sources: IOP PhysicsWorld and the University of Kansas

The post Nearby Supernovas Showered Earth With Iron appeared first on Universe Today.

Posted by Nelio Inacio at 12:15 PM 0 comments

New Horizons Did Amazing Work Before Even Arriving At Pluto

New Horizons Did Amazing Work Before Even Arriving At Pluto:



The solar wind data collected by New Horizons will help create more accurate models of the space environment in our Solar System. Image: NASA's Goddard Space Flight Center Scientific Visualization Studio, the Space Weather Research Center (SWRC) and the Community-Coordinated Modeling Center (CCMC), Enlil and Dusan Odstrcil (GMU)


Anybody with an ounce of intellectual curiosity (and an internet connection) has seen the images of Pluto and its system taken by the New Horizons probe. The images and data from New Horizons have opened the door to Pluto's atmosphere, geology, and composition. But New Horizons wasn't entirely dormant during its 9 year, billion-plus mile journey to Pluto.New Horizons returned 3 years worth of data on the solar wind that sweeps through the near-emptiness of space. The solar wind is the stream of particles that is released from the upper atmosphere of the Sun, called the corona. The Sun's solar wind is what creates space weather in our solar system, and the wind itself varies in temperature, speed, and density.The solar wind data from New Horizons, which NASA calls an "unprecedented set of observations," is filling in a gap in our knowledge. Observatories like the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO) are studying the Sun up close, and the Voyager probes have sampled the solar wind near the edge of the heliosphere, where the solar wind meets interstellar space, but New Horizons is giving us our first look at the solar wind in Pluto's region of space.

pluto-space-wx-sim
This solar wind data should shed some light on a number of things, including the dangerous radiation astronauts face when in space. There is a type of particle with extreme energy levels called anomalous cosmic rays. When travelling close to Earth, these high-velocity rays can be a serious radiation hazard to astronauts.The data from New Horizons reveals particles that pick up an acceleration boost, which makes them exceed their initial speed. It's thought that these particles could be the precursors to anomalous cosmic rays. A better understanding of this might lead to a better way to protect astronauts.These same rays have other effects further out in space. It looks like they are partly responsible for shaping the edge of the heliosphere; the region in space where the solar wind meets the interstellar medium.New Horizons has also told us something about the structure of the solar wind the further it travels from the Sun. Close to the Sun, phenomena like coronal mass ejections (CMEs) have a clearly discernible structure. And the differences in the solar wind, in terms of velocity, density, and temperature, are also discernible. They're determined by the region of the Sun they came from. New Horizons found that far out in the solar system, these structures have changed."At this distance, the scale size of discernible structures increases, since smaller structures are worn down or merge together," said Heather Elliott, a space scientist at the Southwest Research Institute in San Antonio, Texas, and the lead author of a paper to be published in the Astrophysical Journal. "It’s hard to predict if the interaction between smaller structures will create a bigger structure, or if they will flatten out completely."The Voyager probes measured the solar wind as they travelled through our Solar System into the interstellar medium. They've told us a lot about the solar wind in the more distant parts of our system, but their instruments aren't as sensitive and advanced as New Horizons'. This second data set from New Horizons is helping to fill in the blanks in our knowledge.

The post New Horizons Did Amazing Work Before Even Arriving At Pluto appeared first on Universe Today.

Posted by Nelio Inacio at 12:15 PM 0 comments

Venus Compared to Earth

Venus Compared to Earth:



Earth and Venus. Image credit: NASA


Venus is often referred to as "Earth's Twin" (or "sister planet"), and for good reason. Despite some rather glaring differences, not the least of which is their vastly different atmospheres, there are enough similarities between Earth and Venus that many scientists consider the two to be closely related. In short, they are believed to have been very similar early in their existence, but then evolved in different directions.Earth and Venus are both terrestrial planets that are located within the Sun's Habitable Zone (aka. "Goldilocks Zone") and have similar sizes and compositions. Beyond that, however, they have little in common. Let's go over all their characteristics, one by one, so we can in what ways they are  different and what ways they are similar.

Size, Mass and Orbit:

In terms of their respective sizes, masses and compositions, Venus and Earth are quite similar. Whereas Earth has a mean radius of 6,371 km and a mass 5,972,370,000 quadrillion kg, Venus has a mean radius of about 6,052 km and a mass of 4,867,500,000 quadrillion kg. This means that Venus is roughly 0.9499 the size of Earth and 0.815 as massive. In terms of volume, the two planets are almost neck and neck, with Venus possessing 0.866 as much volume as Earth (928.45 billion cubic km compared to Earth's 1083.21 billion). https://youtu.be/euhLuWNEi0gBut when it comes to orbit, the two planets are a bit different. Earth orbits the Sun at an average distance (semi-major axis) of 149,598,023 km (92,955,902 mi), ranging from 147,095,000 km (91,401,000 mi) at perihelion to 152,100,000 km (94,500,000 mi) at aphelion. Venus, meanwhile, orbits the Sun at an average distance of 108,208,000 km, ranging from 107,477,000 km at perihelion to 108,939,000 km. Basically, Venus orbits closer to our Sun and with an eccentricity that is less than one-third that of Earth's (0.006772 compared to 0.0167086). In addition, Earth's axis is tilted far more than Venus' towards the Solar ecliptic - 23.5° compared to Venus' 2.64°. This greater proximity to the Sun is largely responsible for Venus' runaway greenhouse effect, and the low eccentricity (combined with the minor tilt in its axis) results in very little variation in temperature (see below).

Structure and Composition:

Being terrestrial planets, Venus and Earth have similar structures and compositions. Earth's interior is divided into layers based on their chemical or physical properties, consisting of a core, mantle, and outer crust. Whereas the core region consists of nickel and iron, the mantle and outer crust are composed of silicate rock and minerals.While little direct information exists about Venus' seismology, its similarity in size and density to Earth suggests that it has a similar internal structure - consisting of a core, mantle and crust. Like that of Earth, the Venusian core is at least partially liquid because the two planets have been cooling at about the same rate.The principal difference between the two planets is the lack of evidence for plate tectonics on Venus, possibly because its crust is too strong to subduct without water to make it less viscous. This results in reduced heat loss from the planet, preventing it from cooling.Another major difference is that Earth's core is divided between an inner and outer core. Whereas the outer core is believed to consist of a low viscosity liquid, the inner core is believed to be solid. The liquid outer core also rotates in the opposite direction as the planet, producing a dynamo effect that is believed to be the source of Earth's magnetosphere (see below).

Surface Features:

Unlike other planet’s in our Solar System, the majority of Earth’s surface is covered in liquid water. In fact, about 70.8% of the surface is covered by oceans, lakes, rivers and other sources, with much of the continental shelf below sea level. In addition, Earth’s terrain varies greatly from place to place, regardless of whether or not it is above or below sea level.The submerged surface has mountainous features, as well as undersea volcanoes, oceanic trenches, submarine canyons, oceanic plateaus and abyssal plains. The remaining portions of the surface are covered by mountains, deserts, plains, plateaus, and other landforms. Over long periods, the surface undergoes reshaping due to a combination of tectonic activity and erosion.https://youtu.be/n-kg0GbQkEkVenus' surface, in contrast, has little variation in terms of elevation, with the majority covered by smooth, volcanic plains. In fact, it is estimated that if a terraforming event began to allow for water to accumulate on the surface, roughly 80% of the planet would be below sea level. The majority of the above ground landmass would be in the form of two that formed from the planet's two main highland regions -  Ishtar Terra, located in the northern hemisphere, and Aphrodite Terra, just south of the equator.Venus surface appears to have been shaped by volcanic activity rather than tectonic activity. Though Venus is not more volcanic ally active than Earth, its older crust means that it has several times as many volcanoes as Earth, with 167 measuring over 100 km across. Whereas Earth's oceanic crust is continually recycled by subduction at the boundaries of tectonic plates, and has an average age of about 100 million years, Venus' surface is estimated to be 300–600 million years old.

Atmosphere and Temperature:

Earth’s atmosphere is made up of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. As a rule, air pressure and density decrease the higher one goes into the atmosphere and the farther one is from the surface. However, the relationship between temperature and altitude is more complicated, and may even rise with altitude in some cases.Earth's temperature is also subject to variation depending on the time of day, time of year, and where on the planet the temperature is being measured from. Temperatures variations are the result of changes in Earth's orbit, rotation, and its tilted axis. The average temperature is 14° C, with the hottest recorded temperature being 70.7°C (159°F) in the Lut Desert of Iran and the coldest being -89.2°C (-129°F) at Vostok Station in Antarctica.https://youtu.be/96C1eCaTtvg

Meanwhile, Venus’ surface temperature experiences little to no variation, owing to its dense atmosphere, very slow rotation, and very minor axial tilt. Its mean surface temperature of 735 K (462 °C/863.6 °F) is virtually constant, with little or no change between day and night, at the equator or the poles. The one exception is the highest point on Venus, Maxwell Montes, where atmospheric pressure drops to about 4.5 MPa (45 bar) and the temperature drops to about 655 K (380 °C).

Magnetic Fields:

It is a well known fact that Earth's strong magnetic field is intrinsic to it being able to support life. The main part of this field is generated in the core, the site of a dynamo process that converts the kinetic energy of convective fluid motion into electrical and magnetic field energy. The convection movements in the core are chaotic, causing the magnetic poles to drift and periodically change alignment. This causes field reversals at irregular intervals averaging a few times every million years, the most recent of which occurred approximately 700,000 years ago.The field extends outwards from the core, through the mantle, and up to Earth's surface, where it form a dipole (the poles of which are located close to Earth's geographic poles). At the equator of the magnetic field, the magnetic-field strength at the surface is 3.05 × 10?5 Teslas, with global magnetic dipole moment of 7.91 × 1015 T m3. Ions and electrons of the solar wind, and cosmic rays that would otherwise strip away Earth's atmosphere, are deflected by this magnetosphere.https://youtu.be/BOA_yKsaYwMDuring a magnetic storm, charged particles can be deflected from the outer magnetosphere, directed along field lines into Earth's ionosphere, where atmospheric atoms can be excited and ionized, causing the phenomena known as Aurora Borealis and Aurora Australis.Venus also has a magnetic field, though it is significantly weaker than Earth's. What's more, Venus' magnetic field is induced by an interaction between the ionosphere and the solar wind rather than by an internal dynamo in the core like the one inside Earth. Venus's small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation.

This implies that Venus is missing a dynamo, most likely because of a lack of convection in its core. This may have been a result of a global resurfacing event that shut down plate tectonics and led to a reduced heat flux through the crust. This caused the mantle temperature to increase, thereby reducing the heat flux out of the core.

Conclusions:

So let's review. Earth and Venus have their share of similarities, but also some rather stark differences. Let's compare them, category by category, placing Earth's values on the left and Venus' on the right.Mean Radius:                6,371.0 km                   6,051.8 ± 1.0 km    Mass:                                5.972 37 x 1024 kg       4.8675 x 1024 kgVolume:                           10.8321×1011 km3       9.2843×1011 km3Semi-Major Axis:         149,598,023 km          108,208,000 kmAir Pressure:                 101.325 kPa                   9200 kPa Gravity:                            9.8 m/s²                        8.87 m/s2Avg. Temperature:      14°C (57.2 °F)               462 °C (863.6 °F)Temp. Variations:      ±160 °C (278°F)            640 C ()Axial Tilt:                         23.5°                               2.64°Length of Day:               24 hours                        117 days Length of Year:             365 days                       224.7 days Rotation:                         Prograde                       Retrograde Water:                              Yes                                  No Polar Ice Caps:               Yes                                 NoAs you can see, things are run the gambit from being very close, to very different. If people are to call Venus home someday, we'll have to do some serious renovating to bring the planet up to code!We have written many interesting articles about Venus here at Universe Today. Here's The Planet Venus, Interesting Facts About Venus, What Is The Average Surface Temperature On Venus?  Colonizing Venus With Floating Cities and How Do We Terraforming Venus?For more information, check out the Hubblesite's News Releases about Venus, and here's NASA's Solar System Exploration Guide to Venus.Astronomy Cast also has an interesting episode about the planet Venus. Listen to it here, Episode 50: Venus.

The post Venus Compared to Earth appeared first on Universe Today.

Posted by Nelio Inacio at 12:13 PM 0 comments

Supermassive Black Hole Found In The Cosmic Boonies

Supermassive Black Hole Found In The Cosmic Boonies:



A supermassive black hole has been found in an unusual spot: an isolated region of space where only small, dim galaxies reside. Image credit: NASA/JPL-Caltech


Astronomers have found a massive black hole in a place they never expected to find one. The hole comes in at 17 billion solar masses, which makes it the second largest ever found. (The largest is 21 billion solar masses.) And though its enormous mass is noteworthy, its location is even more intriguing.Supermassive black holes are typically found at the centers of huge galaxies. Most galaxies have them, including our own Milky Way galaxy, where a comparatively puny 4 million solar mass black hole is located. Not only that, these gargantuan holes tend to be located in galaxies that are part of a large cluster of galaxies. Being surrounded by all that mass is a prerequisite for the formation of supermassive black holes. The largest one known, at 21 billion solar masses, is located in a very dense region of space called the Coma Cluster, where over 1,000 galaxies have been identified.The largest supermassive holes also tend to be surrounded by bright companions, who have also grown large from the plentiful mass in their surroundings. (Of course, its not the black holes that are bright, but the quasars that surround them.) The long and the short of it is that supermassive black holes are usually found in galaxy clusters, and usually have other supermassive companions in the same region of space. They're not found in isolation.But this newly found black hole is in a rather sparse region of space. It's in NGC 1600, an elliptical galaxy in the constellation Eridanus, 200 million light years from Earth. NGC 1600 is not a particularly large galaxy, and though it has been considered part of a larger group of galaxies, all its companions are much dimmer in comparison. So NGC 1600 is a rather small, isolated galaxy, with only a few dim companions.There's another way that supermassive holes can form. Instead of growing large over time, by feeding on the mass of their home galaxies and galaxy clusters, they can form when two galaxies merge, and two smaller holes become one. But even this requires that they be in a region where galaxies are plentiful, allowing for more collisions and mergers.It may be possible that NGC is the result of a merger of two galaxies, or that it is two black holes that are currently merging. Or it could be that NGC 1600's region of space was once extremely rich in gas, in the early days of the Universe, and that's what gave rise to this 'out of place' supermassive black hole.There is much to be learned about the conditions that give rise to these behemoth black holes. The MASSIVE study will combine several telescopes to survey and catalogue the largest galaxies and black holes. This should tell astronomers a lot about their distribution, and about the circumstances that allow them to exist. We might find even larger ones.

The post Supermassive Black Hole Found In The Cosmic Boonies appeared first on Universe Today.

Posted by Nelio Inacio at 12:12 PM 0 comments

A Star With A Disk Of Water Ice? Meet HD 100546

A Star With A Disk Of Water Ice? Meet HD 100546:



Young stars have a disk of gas and dust around them called a protoplanetary disk. Out of this disk planets are formed, and the presence of water ice in the disc affects where different types of planets form. Credit: NASA/JPL-Caltech


It might seem incongruous to find water ice in the disk of gas and dust surrounding a star. Fire and ice just don't mix. We would never find ice near our Sun.But our Sun is old. About 5 billion years old, with about 5 billion more to go. Some younger stars, of a type called Herbig Ae/Be stars (after American astronomer George Herbig,) are so young that they are surrounded by a circumstellar disk of gas and dust which hasn't been used up by the formation of planets yet. For these types of stars, the presence of water ice is not necessarily unexpected.Water ice plays an important role in a young solar system. Astronomers think that water ice helps large, gaseous, planets to form. The presence of ice makes the outer section of a planetary disk more dense. This increased density allows the cores of gas planets to coalesce and form.Young solar systems have what is called a snowline. It is the boundary between terrestrial and gaseous planets. Beyond this snowline, ice in the protoplanetary disk encourages gas planets to form. Inside this snowline, the lack of water ice contributes to the formation of terrestrial planets. You can see this in our own Solar System, where the snowline must have been between Mars and Jupiter.A team of astronomers using the Gemini telescope observed the presence of water ice in the protoplanetary disk surrounding the star HD 100546, a Herbig Ae/Be star about 320 light years from us. At only 10 million years old, this star is rather young, and it is a well-studied star. The Hubble has found complex, spiral patterns in the disk, and so far these patterns are unexplained.HD 100546 is also notable because in 2013, research showed the probable ongoing formation of a planet in its disk. This presented a rare opportunity to study the early stages of planet formation. Finding ice in the disk, and discovering how deep it exists in the disk, is a key piece of information in understanding planet formation in young solar systems.Finding this ice took some clever astro-sleuthing. The Gemini telescope was used, with its Near-Infrared Coronagraphic Imager (NICI), a tool used to study gas giants. The team installed H2O ice filters to help zero in on the presence of water ice. The protoplanetary disk around young stars, as in the case of HD 100546, is a mixed up combination of dusts and gases, and isolating types of materials in the disk is not easy.Water ice has been found in disks around other Herbig Ae/Be stars, but the depth of distribution of that ice has not been easy to understand. This paper shows that the ice is present in the disk, but only shallowly, with UV photo desorption processes responsible for destroying water ice grains closer to the star.It may seem trite so say that more study is needed, as the authors of the study say. But really, in science, isn't more study always needed? Will we ever reach the end of understanding? Certainly not. And certainly not when it comes to the formation of planets, which is a pretty important thing to understand.

The post A Star With A Disk Of Water Ice? Meet HD 100546 appeared first on Universe Today.

Posted by Nelio Inacio at 12:11 PM 0 comments

NGC 6357: Cathedral to Massive Stars

NGC 6357: Cathedral to Massive Stars:

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2016 March 27


See Explanation. Clicking on the picture will download the highest resolution version available.


NGC 6357: Cathedral to Massive Stars

Image Credit: NASA, ESA and Jesús Maíz Apellániz (IAA, Spain); Acknowledgement: Davide De Martin (ESA/Hubble)


Explanation: How massive can a normal star be? Estimates made from distance, brightness and standard solar models had given one star in the open cluster Pismis 24 over 200 times the mass of our Sun, making it one of the most massive stars known. This star is the brightest object located just above the gas front in the featured image. Close inspection of images taken with the Hubble Space Telescope, however, have shown that Pismis 24-1 derives its brilliant luminosity not from a single star but from three at least. Component stars would still remain near 100 solar masses, making them among the more massive stars currently on record. Toward the bottom of the image, stars are still forming in the associated emission nebula NGC 6357. Appearing perhaps like a Gothic cathedral, energetic stars near the center appear to be breaking out and illuminating a spectacular cocoon.

Tomorrow's picture: Orion Mountain


< | Archive | Submissions | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >


Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
NASA Web Privacy Policy and Important Notices
A service of: ASD at NASA / GSFC
& Michigan Tech. U.

Posted by Nelio Inacio at 12:10 PM 0 comments
Subscribe to: Posts (Atom)