Photos of Nature | Nature Photography What is The Universe

Thursday, January 22, 2015

The Entire Milky Way Might Be a Huge Wormhole That’s Stable and Navigable

The Entire Milky Way Might Be a Huge Wormhole That’s Stable and Navigable:

Artist rendering of a wormhole connecting two galaxies. Credit: Davide and Paolo Salucci.

Our very own Milky Way could be home to a giant tunnel in spacetime.

At least, that’s what the authors of a new study have proposed. According to the team, a collaboration between Indian, Italian, and North American researchers at the International School for Advanced Studies (SISSA) in Italy, the central halo of our galaxy may harbor enough dark matter to support the creation and sustenance of a “stable and navigable” shortcut to a distant region of spacetime – a phenomenon known as a wormhole.

Wormholes were first conceptualized by Albert Einstein and Nathan Rosen in 1935. Far from being fodder for science fiction, the two scientists instead proposed their idea as a way to get around the idea of black hole singularities. Rather than creating a knot of infinite density, Einstein and Rosen thought, the hefty energy inherent in such a massive body would distort spacetime to such an extent that it bent over on itself, allowing a bridge to form between two distant areas of the Universe. Alas, these wormholes would be extremely unstable and would require enormous amounts of “negative energy” to remain open.

A graphic of the structure of a theorized wormhole (NASA)

But according to the team at SISSA, large amounts of dark matter could provide this fuel. Using a model of dark matter’s abundance that is based on the rotation curves of other spiral galaxies, the researchers found that the distribution of dark matter in the Milky Way produced solutions in general relativity that would, theoretically, allow a stable wormhole to arise.

Paulo Salucci, an astrophysicist on the the team from SISSA, explained: “If we combine the map of the dark matter in the Milky Way with the most recent Big Bang model to explain the universe and we hypothesise the existence of space-time tunnels, what we get is that our galaxy could really contain one of these tunnels, and that the tunnel could even be the size of the galaxy itself.” He continued, “But there’s more. We could even travel through this tunnel, since, based on our calculations, it could be navigable. Just like the one we’ve all seen in the recent film Interstellar.”

Of course, Salucci and the other researchers were working on this project long before Interstellar was released, but their result does lend some theoretical support to the ideas in the film – ideas that were also fact-tested and revised by physics guru Kip Thorne of Caltech.

The authors believe that their result reinforces the importance of discerning the true nature of dark matter. According to Salucci, “Dark matter may be ‘another dimension’, perhaps even a major galactic transport system. In any case, we really need to start asking ourselves what it is”.

It is important to understand that this is purely a mathematical result. Indeed, such a wormhole may be theroretically possible… but that doesn’t mean it’s probable. Salucci ventured, “Obviously we’re not claiming that our galaxy is definitely a wormhole, but simply that, according to theoretical models, this hypothesis is a possibility.”

The researchers went on to explain that their idea could be tested experimentally by comparing our own Milky Way, a spiral galaxy, with a nearby galaxy of a different type. By comparing the dark matter distributions between the two galaxies, scientists would potentially be able to use general relativity to probe differences in their spacetime dynamics.

Realistically, the technology that would allow researchers to do that is a long way off. But never fear, science (and scifi) fans – you can still check out the team’s wormhole simulation in the animation below, watch the movie if you haven’t already, and/or get your hands on a copy of Kip Thorne’s book, The Science of Interstellar.

The team’s research was published in the November 2014 issue of Annals of Physics. A pre-print of the paper is available here.

About Vanessa Janek

Vanessa earned her bachelor's degree in Astronomy and Physics in 2009 from Wheaton College in Massachusetts. Her credits in astronomy include observing and analyzing eclipsing binary star systems and taking a walk on the theory side as a NSF REU intern, investigating the expansion of the Universe by analyzing its traces in observations of type 1a supernovae. In her spare time she enjoys writing about astrophysics, cosmology, biology, and medicine, making delicious vegetarian meals, taking adventures with her husband and/or Nikon D50, and saving the world.

Wednesday, January 21, 2015

Here’s Ceres Compared to All the Other Asteroids We’ve Visited

Here’s Ceres Compared to All the Other Asteroids We’ve Visited:

Ceres compared to asteroids visited to date, including Vesta, Dawn’s mapping target in 2011. Image by NASA/ESA/JAXA. Compiled by Paul Schenck.

When the Dawn mission was in its planning stages, Ceres was considered an asteroid. But in 2006, a year before the mission launched, the International Astronomical Union formed a new class of solar system objects known as dwarf planets, and since by definition a dwarf planet is spherical and travels in an orbit around the Sun, Ceres fit that definition perfectly.

But since it’s located in the Asteroid Belt, we still tend to think of Ceres as an asteroid. So, how does Ceres compare to other asteroids?

Dr. Paul Schenk, who is a participating scientist on the Dawn mission, recently put together some graphics on his website and the one above compares Ceres to other asteroids that we’ve visited with spacecraft.

Of course, Ceres is bigger (it’s the biggest object in the Asteroid Belt) and more spherical than the other asteroids. When it comes right down to it, Ceres doesn’t look much like an asteroid at all!

“Ceres is most similar in size to several of Saturn’s icy moons and may be similar internally as well, being composed of 25% water ice by mass,” Schenk noted on his website.

Comparisons of Ceres with other prominent icy objects. Dione is Ceres’ closest twin in size and mass. Image credit: NASA/ESA. Compiled by Paul Schenk.

And water is one of the most interesting and mysterious aspects of Ceres. A year ago, the Herschel space telescope discovered water vapor around Ceres, and the vapor could be emanating from water plumes — much like those that are on Saturn’s moon Enceladus – or it could be from cryovolcanism from geysers or icy volcano.

“The water vapor question is one of the most interesting things we will look for,” Schenk told Universe Today. “What is its source, what does it indicate about the interior and activity level within Ceres? Is Ceres active, very ancient, or both? Does it go back to the earliest Solar System? Those are the questions we hope to answer with Dawn.”

Some scientists also think Ceres may have an ocean and possibly an atmosphere, which makes Dawn’s arrival at Ceres in March one of the most exciting planetary events of 2015, in addition to New Horizon’s arrival at Pluto.

“Since we don’t know why the water vapor venting has happened, or even if it continues, it’s hard to say much more than that,” Schenk said via email, “but it is theoretically possible that some liquid water still exists within Ceres. Dawn will try to determine if that is true.”

One of the possibilities that has been discussed is that if the water vapor is confirmed, Ceres could potentially host microbial life. I asked Schenk what other factors would have to be present in order for that to have occurred?

“The presence of carbon molecules is often regarded as necessary for life,” he replied, “and we think we see that on the surface spectroscopically in the form of carbonates and clays. So, I think the questions will be, whether there is actually liquid water of any kind, whether the carbon compounds are just a surface coating or in the interior, and whether Ceres has ever been warm. If those are true then some sort of prebiotic or biotic activity is in play.”

Since we do not know the answer to any of these questions yet, Schenk says Dawn’s visit to Ceres should be interesting!

On thing of note is that Dawn is now closing in on Ceres and just today, the team released the best image we have yet of Ceres, which you can see in our article here.

Read more of Schenk’s article, “Year of the ‘Dwarves': Ceres and Pluto Get Their Due.”

Keep tabs on the Dawn mission by following Universe Today, or see the Dawn mission website.

How Big Is The Milky Way?

How Big Is The Milky Way?:

The summertime Milky Way from Scorpius to Cygnus is broader and brighter than the winter version because we look into the direction of its center. Credit: Stephen Bockhold

The Milky Way is our home galaxy, the spot where the Earth resides. We are not anywhere near the center — NASA says we’re roughly 165 quadrillion miles from the galaxy’s black hole, for example — which demonstrates just how darn big the galaxy is. So how big is it, and how does it measure up with other neighborhood residents?

The numbers are pretty astounding. NASA estimates the galaxy at 100,000 light-years across. Since one light year is about 9.5 x 10¹²km, so the diameter of the Milky Way galaxy is about 9.5 x 10¹⁷ km in diameter. The thickness of the galaxy ranges depending on how close you are to the center, but it’s tens of thousands of light-years across.

Our galaxy is part of a collection known as the Local Group. Because some of these galaxies are prominent in our sky, the names tend to be familiar. The Milky Way is on a collision course with the most massive member of the group, called M31 or the Andromeda Galaxy. The Milky Way is the second-largest member, with M33 (the Triangulum Galaxy) the third-largest, NASA says. Andromeda appears much brighter in the night sky due to its size and relatively closer distance. There are about 30 members of this group.

The Andromeda Galaxy will collide with the Milky Way in the future. Credit: Adam Evans

Because we are inside the Milky Way’s arms, it appears as a band of stars (or a fuzzy white band) across the Earth’s sky. Casting a pair of binoculars or a telescope across it shows a mix of lighter areas and darker areas; the darker areas are dust that obscures any light from stars, galaxies and other bright objects behind it. From the outside, however, astronomers say the Milky Way is a barred spiral galaxy — a galaxy that has a band of stars across its center as well as the spiral shape.

If you’re looking for the center of the galaxy, gaze at the constellation Sagittarius, which is low on the summer sky horizon for most northern hemisphere residents. The constellation contains a massive radio source known as Sagittarius A*. Astronomers using the Chandra space telescope discovered why this supermassive black hole is relatively weak in X-rays: it’s because hot gas is being pulled inside the nebula, and most of it (99%) gets ejected and diffused.

Sagittarius A in infrared (red and yellow, from the Hubble Space Telescope) and X-ray (blue, from the Chandra space telescope). Credit: X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI

Based on observing globular clusters (star clusters) in the galaxy, astronomers have estimated the Milky Way’s overall age at 13.5 billion years old — just two million years younger than the rest of the universe.

However, scientists are beginning to think that different parts of the galaxy formed at different times. In 2012, for example, astronomers led by Jason Kalirai of the Space Telescope Science Institute pinned down the age of the Milky Way’s inner halo of stars: 11.5 billion years old. They used white dwarfs, the burned-out remnants of Sun-like stars, to make that measurement.

Kalirai’s group’s research indicates that the Milky Way formed in the following sequence: the halo (including globular star clusters and dwarf galaxies), the inner halo (whose stars were born as a result of this construction) and the outer halo (created when the Milky Way ate up nearby ancient dwarf galaxies).

Artist’s impression of the structure of the Milky Way’s halo. Credit: NASA, ESA, and A. Feild (STScI)

While we’ve been focusing on the parts of the galaxy that you can see, in reality most of its mass is made up of dark matter. NASA estimates that there is about 10 times the mass of dark matter than the visible matter in the universe. (Dark matter is a form of matter that we cannot sense with conventional telescopic instruments, except through its gravitational effect on other things such as galaxies. When masses gather in high enough concentrations, they can bend the light of other objects.)

We have written many articles about the Milky Way for Universe Today. Here’s an article about the rotation of Milky Way, and here are some facts about the Milky Way. We’ve also recorded an episode of Astronomy Cast about galaxies. Listen here, Episode 97: Galaxies.

About Elizabeth Howell

Elizabeth Howell is the senior writer at Universe Today. She also works for Space.com, Space Exploration Network, the NASA Lunar Science Institute, NASA Astrobiology Magazine and LiveScience, among others. Career highlights include watching three shuttle launches, and going on a two-week simulated Mars expedition in rural Utah. You can follow her on Twitter @howellspace or contact her at her website.

Rare Triple Transit! There’ll be 3 Moon Shadows on Jupiter on January 24th, 2015

Rare Triple Transit! There’ll be 3 Moon Shadows on Jupiter on January 24th, 2015:

The triple shadow transit of October 12th, 2013. Credit & copyright: John Rozakis.

Play the skywatching game long enough, and anything can happen.

Well, nearly anything. One of the more unique clockwork events in our solar system occurs this weekend, when shadows cast by three of Jupiter’s moons can be seen transiting its lofty cloud tops… simultaneously.

How rare is such an event? Well, Jean Meeus calculates 31 triple events involving moons or their shadows occurring over the 60 year span from 1981 to 2040.

But not all are as favorably placed as this weekend’s event. First, Jupiter heads towards opposition just next month. And of the aforementioned 31 events, only 9 are triple shadow transits. Miss this weekend’s event, and you’ll have to wait until March 20^th, 2032 for the next triple shadow transit to occur.

Hubble spies a triple shadow transit on March 28th, 2004 . Credit: NASA/JPL/Arizona.

Of course, double shadow transits are much more common throughout the year, and we included some of the best for North America and Europe in 2015 in our 2015 roundup.

The key times when all three shadows can be seen crossing Jupiter’s 45” wide disk are on the morning of Saturday, January 24^th starting at 6:26 Universal Time (UT) as Europa’s shadow ingresses into view, until 6:54 UT when Io’s shadow egresses out of sight. This converts to 1:26 AM EST to 1:54 AM EST. The span of ‘triplicate shadows’ only covers a period of slightly less than 30 minutes, but the action always unfolds fast in the Jovian system with the planet’s 10 hour rotation period.

The view at 6:41 UT/1:41 AM EST. Credit: Created using Starry Night Education software.

The view on January 24th at 6:41 UT/1:41 AM EST. Credit: Created using Starry Night Education software.

Unfortunately, the Great Red Spot is predicted to be just out of view when the triple transit occurs, as it crosses Jupiter’s central meridian over three hours later at 10:28 UT.

The moons involved in this weekend’s event are Io, Callisto and Europa. Now, I know what you’re thinking. Seeing three shadows at once is pretty neat, but can you ever see four?

The short answer is no, and the reason has to do with orbital resonance.

The orbital resonance of the three innermost Galilean moons. (Credit: Wikimedia Commons).

The three innermost Galilean moons of Jupiter (Io, Europa and Ganymede) are locked in a 4:2:1 resonance. Unfortunately, this resonance assures that you’ll always see two of the innermost three crossing the disk of Jupiter, but never all three at once. Either Europa or Ganymede is nearly always the “odd moon out.”

To complete a ‘triple play,’ outermost Callisto must enter the picture. Trouble is, Callisto is the only Galilean moon that can ‘miss’ Jupiter’s disk from our line of sight. We’re lucky to be in an ongoing season of Callisto transits in 2015, a period that ends in July 2016.

Perhaps, on some far off day, a space tourism agency will offer tours to that imaginary vantage point on the surface of one of Jupiter’s moons such as Callisto to watch a triple transit occur from close up. Sign me up!

Jupiter currently rises in late January around 5:30 PM local, and sets after sunrise. It is also well placed for northern hemisphere observers in Leo at a declination 16 degrees north . This weekend’s event favors Europe towards local sunrise and ‘Jupiter-set,’ and finds the gas giant world well-placed high in the sky for all of North America in the early morning hours of the 24^th.

Jupiter rides high to the south at 1:45 AM EST for the US East Coast. Credit: Stellarium.

Look closely. Do the shadows of the individual moons appear different to you at the eyepiece? It’s interesting to note during a multiple transit that not all Jovian moon shadows are ‘created equal’. Distant Callisto casts a shadow that’s broad, with a ragged gray and diffuse rim, while the shadow of innermost Io appears as an inky black punch-hole dot. If you didn’t know better, you’d think those alien monoliths were busy consuming Jupiter in a scene straight out of the movie 2010. Try sketching multiple shadow transits and you’ll soon find that you can actually identify which moon is casting a shadow just from its appearance alone.

The orientation of Earth’s nighttime shadow at mid-triple transit. Credit: Created using Orbitron.

Other mysteries of the Galilean moons persist as well. Why did late 19^th century observers describe them as egg-shaped? Can visual observers tease out such elusive phenomena as eruptions on Io by measuring its anomalous brightening? I still think it’s amazing that webcam imagers can now actually pry out surface detail from the Galilean moons!

The 2004 triple shadow transit. Photo by author.

Observing and imaging a shadow transit is easy using a homemade planetary webcam. We’d love to see someone produce a high quality animation of the upcoming triple shadow transit. I know that such high tech processing abilities — to include field de-rotation and convolution mapping of the Jovian sphere — are indeed out there… its breathtaking to imagine just how quickly the fledgling field of ad hoc planetary webcam imaging has changed in just 10 years.

The moons and Jupiter itself also cast shadows off to one side of the planet or the other depending on our current vantage point. We call the point when Jupiter sits 90 degrees east or west of the Sun quadrature, and the point when it rises and sets opposite to the Sun is known as opposition. Opposition for Jupiter is coming right up for 2015 on February 6^th. During opposition, Jupiter and its moons cast their respective shadows nearly straight back.

Did you know: the speed of light was first deduced by Danish astronomer Ole Rømer in 1671 using the discrepancy he noted while predicting phenomena of the Galilean moons at quadrature versus opposition. There were also early ideas to use the positions of the Galilean moons to tell time at sea, but it turned out to be hard enough to see the moons and their shadows with a small telescope based on land, let alone from the pitching deck of a ship in the middle of the ocean.

And speaking of mutual events, we’re still in the midst of a season where it’s possible to see the moons of Jupiter eclipse and occult one another. Check out the USNO’s table for a complete list of events, coming to a sky near you.

And let’s not forget that NASA’s Juno spacecraft is headed towards Jupiter as well., Juno is set to enter a wide swooping orbit around the largest planet in the solar system in July 2016.

Now is a great time to get out and explore Jove… don’t miss this weekend’s triple shadow transit!

Read Dave Dickinson’s sci-fi tale of astronomical eclipse tourism through time and space titled Exeligmos.

About David Dickinson

David Dickinson is an Earth science teacher, freelance science writer, retired USAF veteran & backyard astronomer. He currently writes and ponders the universe from Tampa Bay, Florida.

First Hubble and Now Dawn Have Seen This White Spot on Ceres. What is it?

First Hubble and Now Dawn Have Seen This White Spot on Ceres. What is it?:

Comparison of HST and Dawn FC images of Ceres taken nearly 11 years apart. Credit: NASA.

There’s a big white spot on Ceres and we don’t know what it is. We’ve known about the white spot since the Hubble Space Telescope first captured images of it in 2003 and 2004, and in subsequent images taken by Hubble, the spot remains visible. Now, in images released yesterday from the Dawn spacecraft, currently on approach to Ceres, the spot remains. In the animated image, below, the spot almost seems to glint in the sunlight.

What is it?

Animation of Ceres made from Dawn images acquired on Jan. 13, 2015 (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

One of the most anticipated aspects the Dawn spacecraft being in orbit around Ceres HAS to be finding out what this spot is. It could be ice, it could be a cryovolcano or geysers, or it could be something else. But we do know fairly certain that it is a real feature and not an image artifact, since it shows up in most of the recent Hubble images and now the Dawn images.

Planetary scientists have long suspected that water ice may be buried under Cere’s crust. A few things point to subsurface ice: the density of Ceres is less than that of the Earth’s crust, and because the surface bears spectral evidence of water-bearing minerals. Scientists estimate that if Ceres were composed of 25 percent water, it may have more water than all the fresh water on Earth. Ceres’ water, unlike Earth’s, would be in the form of water ice and located in the mantle, which wraps around the asteroid’s solid core.

And then last year, the Herschel space telescope discovered water vapor around Ceres, and the vapor could be emanating from water plumes — much like those that are on Saturn’s moon Enceladus – or it could be from cryovolcanism from geysers or icy volcanoes. Without huge a planet or satellite nearby tugging on it, the mechanism for how Ceres is active is also intriguing.

Images from the Hubble Space Telescope in 2004 of Ceres. Credit: NASA/Hubble.

Some scientists also think Ceres may have an ocean and possibly an atmosphere.

As we discussed in our article yesterday, with all that water potentially at Ceres, could it theoretically host microbial life? Some scientists have hinted that Ceres and other icy bodies could be a possible source for life on Earth, another intriguing proposition.

Yesterday, I asked Dawn scientist Paul Schenk what other factors would have to be present in order for microbial life to have arisen on Ceres.

“The presence of carbon molecules is often regarded as necessary for life,” he replied, “and we think we see that on the surface spectroscopically in the form of carbonates and clays. So, I think the questions will be, whether there is actually liquid water of any kind, whether the carbon compounds are just a surface coating or in the interior, and whether Ceres has ever been warm. If those are true then some sort of prebiotic or biotic activity is in play.”

And we’ll soon find out more about this intriguing dwarf planet.

This processed image, taken Jan. 13, 2015, shows the dwarf planet Ceres as seen from the Dawn spacecraft. The image hints at craters on the surface of Ceres. Dawn’s framing camera took this image at 238,000 miles (383,000 kilometers) from Ceres. Credit:
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

As the deputy principal investigator for Dawn, Carol Raymond said following the Herschel water vapor discovery, “We’ve got a spacecraft on the way to Ceres, so we don’t have to wait long before getting more context on this intriguing result, right from the source itself.”

NASA says that Dawn’s images will surpass Hubble’s resolution at the next imaging opportunity, which will be at the end of January.

The spacecraft arrives at Ceres on March 6, when it will be captured into orbit. The images will continue to improve as the spacecraft spirals closer to the surface during its 16-month study of the dwarf planet. Dawn will eventually be about 1,000 times closer to Ceres than it was for the images released yesterday and therefore will provide 1,000 times as much detail. Dawn at Ceres is primarily a mapping mission, so it will map the geology and chemistry of the surface in high resolution.

It should reveal the processes that drive the outgassing activity, and it should reveal how much water this dwarf planet holds.

And it should reveal the mystery of that white spot.

If Earth Had Saturn’s Rings, This is What it Would Look Like

If Earth Had Saturn’s Rings, This is What it Would Look Like:

A graphic depicting Earth and Saturn’s rings to scale. Credit: John Brady/Astronomy Central.

We Earthlings love to dream, conjure and extrapolate. If you pose a question such as, “What if Earth had Saturn’s rings?” with all the resources available these days someone will not only answer the question but create some beautiful graphics to depict it! Yesterday, we saw this amazing graphic posted on reddit of a to-scale depiction of how Earth would look like with Saturn’s rings, and thanks to those who helped find the original source, the original image was created by John Brady at Astronomy Central. (We apologize… we originally credited the wrong person).

Of course, “What if Earth had Saturn’s rings?” is not a new question. In fact we’ve discussed it previously on Universe Today, and in 2013, illustrator and author Ron Miller put together some incredible visualizations of what Earth’s skies would look like with Saturn’s rings.

Also, last year someone on imgur put together a wonderful set of images of Earth with Saturn’s rings, as it would look from Earth’s Moon:

This video depicts rings around Earth, but the scale of the rings are not the size of Saturn’s:

Phil Plait discussed the problems that might arise for us if there were Earthrings, such as the rings would change the amount of sunlight reaching the Earth, and our view of the night sky would be hampered. And then Earth could potentially be shredded by ring debris.

Oh well, we can dream, can’t we?

See more great size comparisons of things in our Solar System and Universe at John Brady’s post on Astronomy Central, including a look at how many Earth’s would span across Saturn’s rings.

A Swirling Vortex at Venus’ South Pole

A Swirling Vortex at Venus’ South Pole:

A mass of swirling gas and cloud at Venus’ south pole. Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford.

Here’s the latest view of the mass of swirling gas and clouds at Venus’ south pole. The Venus Express’s Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) has been keeping an eye on this polar vortex since the spacecraft arrived and discovered this huge storm in 2006. During the mission, VIRTIS has seen the vortex constantly transform, morphing from a double vortex into a squashed shape and into the eye-like structure seen here.

This image was taken in April 2007 but was just released this week.

Venus has a very choppy and fast-moving atmosphere, even though wind speeds are much slower at the planet’s surface. At the cloud tops about 70 km above the surface, winds can reach 400 km/h. At this altitude, Venus’ atmosphere spins about 60 times faster than the planet itself. Compared to Earth, this is a dizzying speed: even Earth’s fastest winds move at most about 30% of our planet’s rotation speed.

These polar vortices form when heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks.

High velocity winds spin westwards around the planet, and take just four days to complete a rotation. This ‘super-rotation’, combined with the natural recycling of hot air in the atmosphere, would induce the formation of a vortex structure over each pole.

A video of the vortex, made from 10 images taken over a period of five hours, can be seen here. The vortex rotates with a period of around 44 hours.

Source: ESA

Monday, January 19, 2015

Comet Finlay Surprise Outburst, Visible in Binoculars … again!

Comet Finlay Surprise Outburst, Visible in Binoculars … again!:

Comet Finlay in outburst on the evening (CST) of January 16th. Credit: Michael Mattiazzo

Comet Finlay’s up to its old shenanigans again. Here we see it in outburst with a bright, compact head and a half-degree-long tail pointing northeast on Friday, January 16th. Credit: Michael Mattiazzo

Lost sleep at night, fingers tapping on the keyboard by day. Darn comets are keeping me busy! But of course that’s a good problem. Comet 15P/Finlay, which had been languishing in the western sky at dusk at magnitude +10, has suddenly come to life … for a second time.

Two nights ago, Australian comet observer Michael Mattiazzo took a routine picture of Finlay and discovered it at magnitude +8. Today it’s a magnitude brighter and now joins Comet Lovejoy as the second binocular comet of 2015. Comet-wise, we’ve gone from zero to 60 and the new year’s fewer than 3 weeks old!

Comet 15P/Finlay tonight through Feb. 1. Positions shown for 7 p.m (CST) and stars depicted to magnitude +8. Tonight the comet will be right next to a 6th mag. star in Aquarius low in the southwestern sky at nightfall. Mars and Neptune’s position are for Jan. 17th. Click to enlarge. Source: Chris Marriott’s SkyMap software

Comet Finlay’s threw its first tantrum last December when it reached binocular visibility (faintly) shortly before Christmas. Discovered by William Henry Finlay from South Africa on September 26, 1886, the comet circles the Sun every 6.5 years. This time around it reached perihelion on December 27th and spent many nights near the planet Mars low in the western sky. Until the new outburst, the comet had returned to its predicted brightness (~10 magnitude) and departed company with the Red Planet.

Even though photographed under poor conditions on Jan. 17th, Alfons Diepvens' image of Comet Finlay's coma and nuclear region reveals interesting details. Credit: Alfons Diepvens

Even though photographed under poor conditions on Jan. 17th, Belgian amateur astronomer Alfons Diepvens’ image of Comet Finlay’s coma and nuclear region reveals interesting details. Credit: Alfons Diepvens

It’s still low in the west, though not quite so much as in December, in the constellation Aquarius. With an orbit inclined only 6.8° to the ecliptic or plane of the Solar System, you’ll find it chugging eastward across the zodiac at the rate of 1° per night. The best time to view the comet is at the end of evening twilight at nightfall when it’s highest — 20° to 25° above the southwestern horizon.

Comet Lovejoy southwest of the beautiful Pleaides star cluster on January 15th. Credit: Bob King

Comet Lovejoy seen in tandem with the beautiful Pleaides star cluster on January 15th. Click for a finder chart. Credit: Bob King

Right now it’s not far from Lambda Aquarii and will soon glide just south of the well-known asterism called the “Circlet” in Pisces. Currently between 7th and 8th magnitude and showing a bright, condensed center, Comet Finlay is easily visible in 10×50 binoculars. Catch it while you can. These outbursts often fade fairly quickly. While we don’t know its exact cause, what likely happened is that a new fissure opened up on the comet’s surface, exposing fresh ice to sunlight. Rapid vaporization of the new material may be behind the eruption.

While Comet Q2 Lovejoy’s been getting all the attention, Finlay’s back in the game and making mid-January nights all that more enjoyable for sky gazing. Lovejoy is presently passing near the Pleiades star cluster in Taurus. This coming week will be the last dark one before the Moon starts to spoil the view. I hope you’re able to spot both at the next opportunity.

5-degree binocular view of Mars as it approaches Neptune in the next few nights. They’ll be in close conjunction on the 19th. Mars shines at about 1st magnitude, Neptune at 8. Stars shown to mag. 9. Source: Chris Marriott’s SkyMap software

While we’re on the topic, take another look at the finder chart and you’ll see that Mars lies very near Neptune. The two are presently about 2° apart but on Monday Jan. 19th at dusk they’ll be separated by just 12 arc minutes or 1/5 of a degree and easily fit into the same medium-power view of a telescope. Pretty cool – and well worth seeing along with those comets!

About Bob King

I'm a long-time amateur astronomer and member of the American Association of Variable Star Observers (AAVSO). My observing passions include everything from auroras to Z Cam stars. Every day the universe offers up something both beautiful and thought-provoking. I also write a daily astronomy blog called Astro Bob.

How Long Have Humans Been On Earth?

How Long Have Humans Been On Earth?:

Lights from the United States glow in this night image based on data taken from the Suomi NPP satellite in April and October 2012. Credit: NASA Earth Observatory/NOAA NGDC

While our ancestors have been around for about six million years, the modern form of humans only evolved about 200,000 years ago. Civilization as we know it is only about 6,000 years old, and industrialization started in the earnest only in the 1800s. While we’ve accomplished much in that short time, it also shows our responsibility as caretakers for the only planet we live on right now.

The effects of humans on Earth cannot be understated. We’ve been able to survive in environments all over the world, even harsh ones such as Antarctica. Every year, we fell forests and destroy other natural areas, driving species into smaller areas or into endangerment, because of our need to build more housing to contain our growing population.

With seven billion people on Earth, pollution from industry and cars is a growing element in climate change — which affects our planet in ways we can’t predict. But we’re already seeing the effects in melting glaciers and rising global temperatures.

Enormous chuck of ice breaks off the Petermann Glacier in Greenland. Credit: NASA.

The first tangible link to humanity started around six million years ago with a primate group called Ardipithecus, according to the Smithsonian Institution. Based in Africa, this group began the path of walking upright. This is traditionally considered important because it allowed for more free use of the hands for toolmaking, weaponry and other survival needs.

The Australopithecus group, the museum added, took hold between about two million and four million years ago, with the abilities to walk upright and climb trees. Next came Paranthropus, which existed between about one million and three million years ago. The group is distinguished by its larger teeth, giving a wider diet.

The Homo group — including our own species, Homo sapiens — began arising more than two million years ago, the museum said. It’s distinguished by bigger brains, more tool-making and the ability to reach far beyond Africa. Our species was distinguished about 200,000 years ago and managed to survive and thrive despite climate change at the time. While we started in temperate climates, about 60,000 to 80,000 years ago the first humans began straying outside of the continent in which our species was born.

GOCE view of Africa.. Credits: ESA/HPF/DLR, anaglyph by Nathanial Burton-Bradford.

“This great migration brought our species to a position of world dominance that it has never relinquished,” reads a 2008 article in Smithsonian Magazine, pointing out that eventually we obviated the competition (most prominently including Neanderthals and Homo erectus). When the migration was complete,” the article continues, “Homo sapiens was the last—and only—man standing.”

Using genetic markers and an understanding of ancient geography, scientists have partially reconstructed how humans could have made the journey. It’s believed that the first explorers of Eurasia went there using the Bab-al-Mandab Strait that now divides Yemen and Djibouti, according to National Geographic. These people made it to India, then by 50,000 years ago, southeast Asia and Australia.

A little after this time, another group began an inland journey across the Middle East and south-central Asia, positioning them to later go to Europe and Asia, the magazine added. This proved important for North America, as about 20,000 years ago, some of these people crossed over to that continent using a land bridge created by glaciation. From there, colonies have been found in Asia dating as far back as 14,000 years ago.

A teensy-tiny Neil Armstrong is visible in the helmet of Buzz Aldrin during the Apollo 11 landing in July 1969. Credit: NASA

Since this is a space website, it’s also worth noting when humans began leaving Earth. The first human mission to space took place April 12, 1961 when Soviet cosmonaut Yuri Gagarin made a single orbit of Earth in his spacecraft, Vostok 1. Humanity first set foot on another world on July 20, 1969, when Americans Neil Armstrong and Buzz Aldrin walked on the Moon.

Since then, our colonization efforts in space have focused mostly on space stations. The first space station was the Soviet Salyut 1, which launched from Earth April 19, 1971 and was first occupied by Georgi Dobrovolski, Vladislav Vokov, and Viktor Patsayev on June 6. The men died during re-entry June 29 due to spacecraft decompression, meaning no further flights went to that station.

There have been other space stations since. A notable example is Mir, which hosted several long-duration missions of a year or more — including the longest single spaceflight duration of any human to date, 437 days, by Valeri Polyakov in 1994-95. The International Space Station launched its first piece Nov. 20, 1998 and has been continuously occupied by humans since Oct. 31, 2000. The first humans to start the continuous occupation included Expedition 1 members Bill Shepard (U.S.) and Russian cosmonauts Sergei Krikalev and Yuri Gidzenko.

About Elizabeth Howell

Here’s Dawn’s Best View of Ceres Yet

Here’s Dawn’s Best View of Ceres Yet:

Animation of Ceres made from Dawn images acquired on Jan. 13, 2015 (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI)

Just sit back and watch the world turn… or should I say, watch the dwarf planet turn in this fascinating animation from Dawn as the spacecraft continues on its ion-powered approach to Ceres!

The images were captured by Dawn’s framing camera over the course on an hour on Jan. 13 at a distance of 238,000 miles (383,000 km) from Ceres. At 590 miles (950 km) wide Ceres is the largest object in the main asteroid belt.

“Already, the [latest] images hint at first surface structures such as craters,” said Andreas Nathues, lead investigator for the framing camera team at the Max Planck Institute for Solar System Research in Gottingen, Germany. “We have identified all of the features seen by Hubble on the side of Ceres we have observed, and there are also suggestions of remarkable structures awaiting us as we move even closer.”

Although these latest 27-pixel images from Dawn aren’t quite yet better than Hubble’s images from Jan. 2004, very soon they will be.

Comparison of HST and Dawn FC images of Ceres taken nearly 11 years apart

“The team is very excited to examine the surface of Ceres in never-before-seen detail,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles. “We look forward to the surprises this mysterious world may bring.”

Launched Sept. 27, 2007, Dawn previously spent over 13 months in orbit around the asteroid/protoplanet Vesta from 2011–12 and is now on final approach to Ceres. On March 6 Dawn will arrive at Ceres, becoming the first spacecraft to enter orbit around two different target worlds.

Read more: Find Out How “Crazy Engineering” is Getting Dawn to Ceres

Learn more at JPL’s Dawn mission site here, and find out where Dawn is right now here.

Also, read more from the Max Planck Institute for Solar System Research here.

Source: NASA/MPI

About Jason Major

A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!

Where to Look for Comet Lovejoy Until it Fades from Sight

Where to Look for Comet Lovejoy Until it Fades from Sight:

Viewing Comet Lovejoy from dark skies in Portugal. Credit: Miguel Claro

Viewing Comet Lovejoy with binoculars from dark skies in Portugal on January 11th. Credit: Miguel Claro

I hate to admit it, but our dear comet is fading. Only a little though. As Comet Q2 Lovejoy wends its way from Earth toward perihelion and beyond, it will slowly dim and diminish. With an orbital period of approximately 8,000 years it has a long journey ahead. Down here on Earth, we continue to look up every clear night hoping for yet another look at what’s been a wonderful comet.

Comet Lovejoy and the Pleiades on January 19, 2015. Credit: Joseph Brimacombe

Despite its inevitable departure I encourage you to continue following Comet Lovejoy. It’s not often a comet vaults to naked eye brightness, and this one should remain visible without optical aid through mid-February.

Like a human celebrity, Lovejoy’s been the focus of attention from beginners and professionals alike using everything from cheap cellphone cameras to high-end telescopes to capture its magic. Who can get enough of that wildly fluctuating ion tail and greeny-blue coma?

Comet Q2 Lovejoy continues tracking north-northwest now through March. This chart shows the comet’s position at 7 p.m. (CST) every 5 nights through March 5. Stars shown to magnitude +6. Click to enlarge. Created with Chris Marriott’s SkyMap software

The comet continues moving northward all winter long, sliding through the diminutive constellations Aries and Triangulum, across Andromeda and into Cassiopeia, fading as she goes. You can use the map above and binoculars to help you follow it. I like to create lines and triangles using bright stars and deep sky objects to direct me to the comet.

Deep image of Comet Lovejoy taken with a Canon 6D with 50mm f/1.4 lens at f/2. 10 exposure of 30 secs at ISO3200 stacked. The tail, though faint, extends for possibly 18 degrees in this amazing image. Credit: Ian Sharp

Deep image of Comet Lovejoy taken with a Canon 6D with 50mm f/1.4 lens at f/2. Ten exposures of 30 secs at ISO3200 were stacked to create the final photo. The tail extends for possibly 18 degrees in this amazing image. The Pleiades are at top right; Hyades at bottom center. Credit: Ian Sharp

Tonight for instance, Lovejoy one fist held at arm’s length due west of the Pleiades. On the 29th, it’s on a line from Beta Persei (Algol) to Beta Trianguli. On February 3rd, it pulls right up alongside the colorful double star Gamma Andromedae, also called Almach, and on the 8th forms one of the apexes of an equilateral triangle with the two Betas. You get the idea.

The tail rays that show so clearly in photographs as in this image made on January 16th require dark skies and 8-inch or larger telescope to see visually. They're very low contrast. Credit: Greg Redfern

The tail rays that show so clearly in photographs as in this image made on January 16th require dark skies and an 8-inch or larger telescope to see visually. They’re very low contrast. Credit: Greg Redfern

The waxing moon will interfere with viewing beginning next weekend and render the comet nil with the naked eye, you’ll still be able to track it in binoculars during that time. Dark skies return around Feb. 7.

Comet Lovejoy captured from the Dark Sky Alqueva Reserve, Portugal on Jan. 11th by Miguel Claro

Delicate streamers show in Comet Lovejoy’s ion tail in this photo from January 13th. Credit: Bernhard Hubl

About Bob King

Friday, January 16, 2015

What Is The Gibbous Moon?

What Is The Gibbous Moon?:

The Moon. Credit: Logan Mancuso

What does it mean when you hear the term “gibbous moon”? It’s when the Moon is more than half full, but not quite fully illuminated, when you look at it from the perspective of Earth. The reason the light changes has to do with how the Moon orbits the Earth.

The average distance between the Earth and the Moon is about 382,500 km (237,675 miles). As the Moon orbits our planet, the illumination of the Sun changes on its surface. The Moon takes about 29.5 days to go from a new moon to a full moon and then back again. This is called a “synodic period” or sometimes, a “synodic month.”

It’s slightly longer than the “sidereal period” or “sidereal month” (27.3 days) for the Moon to return to the same position relative to the stars. That’s because the Earth is moving at the same time along its orbit of the Sun, requiring the Moon to “catch up” to reach the same illumination, according to NASA.

How the phases of the Moon work. Credit: NASA/Bill Dunford

So as the Moon orbits the Earth, the illumination of the Sun changes. When the Moon is in between the Earth and the Sun — with the three objects perfectly aligned — the angle between the Moon and the Sun is 0 degrees. This produces a “new moon”, which is when the Moon is not illuminated or barely illuminated at all.

The first quarter occurs when the Moon is at a 90-degree angle with the Sun, as seen from Earth. Once the Moon’s angle exceeds 90 degrees, that’s when it enters the waxing gibbous phase. At 180 degrees from the Sun, the Moon is fully illuminated (a full moon). Then after it reaches 180 degrees, when the Moon and the Sun are on the opposite sides of the Earth, it becomes a waning gibbous moon.

At 270 degrees, the Moon finishes its gibbous phase, enters the third quarter of its synodic period and becomes a waning crescent, until it reaches the new moon phase and starts the cycle anew. And actually, the Moon’s position around the Earth plays a role in solar and lunar eclipses.

Total solar eclipse in 1999. The alignment of the nearby Moon and massive Sun, the weightiest body in the Solar System by far, didn't cause anyone to float off the ground. To my knowledge. Credit: Luc Viatour

Total solar eclipse in 1999. Credit: Luc Viatour

A solar eclipse can only happen when the Moon is in its “new phase”. This is, again, because of geometry — because the Moon is in between the Sun and the Earth. From time to time, the position of the Moon lines up with the position of the Sun in Earth’s sky. Coincidentally, the Sun and the Moon appear to be about the same size from Earth’s surface, which makes it possible for the Moon to completely (or almost completely) block the Sun. This creates a solar eclipse. The full eclipse phase can last anywhere from seconds to minutes.

By contrast, a lunar eclipse happens when the Moon is in its “full phase.” At this time, the Earth is in between the Moon and the Sun. When the Moon enters the Earth’s shadow, the shadow can completely or partially fall across the Moon’s surface. A total lunar eclipse phase tends to last anywhere from minutes to over an hour. It creates a ruddy (red or brown) glow due to the effect of sunsets and sunrises all around the Earth shining on the Moon at the same time, according to Bad Astronomy’s Phil Plait.

You’ll notice that as the Moon goes through its various phases, it keeps the same side of itself turned towards Earth. This is due to an effect called tidal locking. After the Moon was formed (likely through a near-cataclysmic collision with Earth), its rotation period didn’t align with that of Earth’s. But over millions of years, the tug of the Earth’s gravity produced a bulge in the Moon’s interior on the side closest to Earth.

Tidal locking results in the Moon rotating about its axis in about the same time it takes to orbit the Earth (left side). If the Moon didn’t spin at all, then it would alternately show its near and far sides to the Earth while moving around our planet in orbit, as shown in the figure on the right. Credit: Wikipedia

As Discovery News explains, over time that bulge was pulled back and forth as the Moon orbited Earth. If the rotation is much slower than the orbit, the bulge “lags behind” while the smaller body orbits. Eventually, this causes one side to always face the larger body.

Tidal locking, by the way, is a fairly common phenomenon in our Solar System — particularly at Jupiter and Saturn, which are massive gas giants that (compared to their immense size) have nat-sized moons orbiting close by. Tidal locking also likely takes place with exoplanets that are orbiting close in to their parent stars.

We have done many stories on Universe Today about the Moon. Here’s one about the phases of the Moon. Want to know when the next full moon is going to be? Here’s a handy guide from NASA that covers the phases of the Moon for 6000 years. And here’s a good explainer on the phases of the Moon. We also discussed the formation of the Moon on Astronomy Cast, Episode 17: Where Did the Moon Come From?

About Elizabeth Howell

NASA Photos Photography

The National Aeronautics and Space Administration (NASA) is the United States government agency responsible for the civilian space program as well as aeronautics and aerospace research. President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA's predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

UFO SIGHTINGS PHOTO PHOTOGRAPHY

The Oxford English Dictionary defines a UFO as "An unidentified flying object; a 'flying saucer'." The first published book to use the word was authored by Donald E. Keyhoe. The acronym "UFO" was coined by Captain Edward J. Ruppelt, who headed Project Blue Book, then the USAF's official investigation of UFOs. He wrote, "Obviously the term 'flying saucer' is misleading when applied to objects of every conceivable shape and performance. For this reason the military prefers the more general, if less colorful, name: unidentified flying objects. UFO (pronounced Yoo-foe) for short." Other phrases that were used officially and that predate the UFO acronym include "flying flapjack", "flying disc", "unexplained flying discs", "unidentifiable object", and "flying saucer". The phrase "flying saucer" had gained widespread attention after the summer of 1947. On June 24, a civilian pilot named Kenneth Arnold reported seeing nine objects flying in formation near Mount Rainier. Arnold timed the sighting and estimated the speed of discs to be over 1,200 mph (1,931 km/h). At the time, he described the objects' shape as being somewhat disc-like or saucer-like, leading to newspaper accounts of "flying saucers" and "flying discs". In popular usage the term UFO came to be used to refer to claims of alien spacecraft. and because of the public and media ridicule associated with the topic, some investigators prefer to use such terms as unidentified aerial phenomenon (or UAP) or anomalous phenomena, as in the title of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP).

UFO PHOTO PHOTOGRAPHY

UFO - Unidentified Flying Object An unidentified flying object, or UFO, in its most general definition, is any apparent anomaly in the sky that is not identifiable as a known object or phenomenon. Culturally, UFOs are associated with claims of visitation by extraterrestrial life or government-related conspiracy theories, and have become popular subjects in fiction. While UFOs are often later identified, sometimes identification may not be possible owing to the usually low quality of evidence related to UFO sightings (generally anecdotal evidence and eyewitness accounts). Stories of fantastical celestial apparitions have been told since antiquity, but the term "UFO" (or "UFOB") was officially created in 1953 by the United States Air Force (USAF) to serve as a catch-all for all such reports. In its initial definition, the USAF stated that a "UFOB" was "any airborne object which by performance, aerodynamic characteristics, or unusual features, does not conform to any presently known aircraft or missile type, or which cannot be positively identified as a familiar object." Accordingly, the term was initially restricted to that fraction of cases which remained unidentified after investigation, as the USAF was interested in potential national security reasons and/or "technical aspects" (see Air Force Regulation 200-2). During the late 1940s and through the 1950s, UFOs were often referred to popularly as "flying saucers" or "flying discs". The term UFO became more widespread during the 1950s, at first in technical literature, but later in popular use. UFOs garnered considerable interest during the Cold War, an era associated with a heightened concern for national security. Various studies have concluded that the phenomenon does not represent a threat to national security nor does it contain anything worthy of scientific pursuit (e.g., 1951 Flying Saucer Working Party, 1953 CIA Robertson Panel, USAF Project Blue Book, Condon Committee).

Photos of Nature | Nature Photography What is The Universe