Friday, January 2, 2015

Moonlight Is a Many-Splendored Thing

Moonlight Is a Many-Splendored Thing:



We see the Moon differently depending upon the wavelength in which we view it. Top row from left:


These are all photos of the Moon but photographed in a variety of different wavelengths of light. The images are arranged from longest to shortest wavelength. Top row from left: Moon in radio waves, submillimeter light, mid-infrared, near-infrared. Bottom row: Visual, ultraviolet, X-rays and gamma rays. Credits (top): NRAO-VLA/U. of British Columbia, Mike Kozubel/MSX Project/NASA-Galileo. Bottom: Bob King/Southwest Research Institute/NASA-ROSAT/Dave Thompson-NASA-GFSC
“By the Light of the Silvery Moon” goes the song. But the color and appearance of the Moon depends upon the particular set of eyes we use to see it. Human vision is restricted to a narrow slice of the electromagnetic spectrum called visible light.

With colors ranging from sumptuous violet to blazing red and everything in between, the diversity of the visible spectrum provides enough hues for any crayon color a child might imagine. But as expansive as the visual world’s palette is, it’s not nearly enough to please astronomers’ retinal appetites.



Visible light is a sliver of light's full range of "colors" which span from kilometers-long, low-energy radio waves (left) to short wavelength, energetic gamma rays. It's all light, with each color determined by wavelength. Familiar objects along the bottom reference light wave sizes. Visible light waves are about one-millionth of a meter wide. Credit: NASA


Visible light is a sliver of light’s full range of “colors” which span from kilometers-long, low-energy radio waves (left) to short wavelength, energetic gamma rays. It’s all light, with each color determined by wavelength. Familiar objects along the bottom reference light wave sizes. Visible light waves are about one-millionth of a meter wide. Credit: NASA
Since the discovery of infrared light by William Herschel in 1800 we’ve been unshuttering one electromagnetic window after another. We build telescopes, great parabolic dishes and other specialized instruments to extend the range of human sight.  Not even the atmosphere gets in our way. It allows only visible light, a small amount of infrared and ultraviolet and selective slices of the radio spectrum to pass through to the ground. X-rays, gamma rays and much else is absorbed and completely invisible.



Earth's atmosphere blocks a good portion of light's diversity from reaching the ground, the reason we launch rockets and orbiting telescopes into space. Large professional telescopes are often built on mountain tops above much of the atmosphere allowing astronomers to see at least some infrared light that is otherwise absorbed by air at lower elevations. Credit: NASA


Earth’s atmosphere blocks a good portion of light’s diversity from reaching the ground, the reason we launch rockets and orbiting telescopes into space. Large professional telescopes are often built on mountain tops above much of the denser, lower atmosphere. This expands the viewing “window” into the infrared. Credit: NASA
To peer into these rarified realms, we’ve lofting air balloons and then rockets and telescopes into orbit or simply dreamed up the appropriate instrument to detect them. Karl Jansky’s homebuilt radio telescope cupped the first radio waves from the Milky Way in the early 1930s; by the 1940s  sounding rockets shot to the edge of space detected the high-frequency sizzle of X-rays.  Each color of light, even the invisible “colors”, show us a new face on a familiar astronomical object or reveal things otherwise invisible to our eyes.

So what new things can we learn about the Moon with our contemporary color vision?



Radio Moon


Radio Moon
Radio: Made using NRAO’s 140-ft telescope in Green Bank, West Virginia. Blues and greens represent colder areas of the moon and reds are warmer regions. The left half  of Moon was facing the Sun at the time of the observation. The sunlit Moon appear brighter than the shadowed portion because it radiates more heat (infrared light) and radio waves.



Submillimeter Moon


Submillimeter Moon
Submillimeter: Taken using the SCUBA camera on the James Clerk Maxwell Telescope in Hawaii. Submillimeter radiation lies between far infrared and microwaves. The Moon appears brighter on one side because it’s being heated by Sun in that direction. The glow comes from submillimeter light radiated by the Moon itself. No matter the phase in visual light, both the submillimeter and radio images always appear full because the Moon radiates at least some light at these wavelengths whether the Sun strikes it or not.



Mid-infrared Moon


Mid-infrared Moon
Mid-infrared: This image of the Full Moon was taken by the Spirit-III instrument on the Midcourse Space Experiment (MSX) at totality during a 1996 lunar eclipse. Once again, we see the Moon emitting light with the brightest areas the warmest and coolest regions darkest. Many craters look like bright dots speckling the lunar disk, but the most prominent is brilliant Tycho near the bottom. Research shows that young, rock-rich surfaces, such as recent impact craters, should heat up and glow more brightly in infrared than older, dust-covered regions and craters. Tycho is one of the Moon’s youngest craters with an age of just 109 million years.



Near-infrared Moon


Near-infrared Moon
Near-infrared: This color-coded picture was snapped just beyond the visible deep red by NASA’s Galileo spacecraft during its 1992 Earth-Moon flyby en route to Jupiter. It shows absorptions due to different minerals in the Moon’s crust. Blue areas indicate areas richer in iron-bearing silicate materials that contain the minerals pyroxene and olivine. Yellow indicates less absorption due to different mineral mixes.



Visible light Moon


Visible light Moon
Visible light: Unlike the other wavelengths we’ve explored so far, we see the Moon not by the light it radiates but by the light it reflects from the Sun.

The iron-rich composition of the lavas that formed the lunar “seas” give them a darker color compared to the ancient lunar highlands, which are composed mostly of a lighter volcanic rock called anorthosite.



UV Moon


UV Moon
Ultraviolet: Similar to the view in visible light but with a lower resolution. The brightest areas probably correspond to regions where the most recent resurfacing due to impacts has occurred. Once again, the bright rayed crater Tycho stands out in this regard. The photo was made with the Ultraviolet Imaging Telescope flown aboard the Space Shuttle Endeavour in March 1995.



X-ray Moon


X-ray Moon
X-ray: The Moon, being a relatively peaceful and inactive celestial body, emits very little x-ray light, a form of radiation normally associated with highly energetic and explosive phenomena like black holes. This image was made by the orbiting ROSAT Observatory on June 29, 1990 and shows a bright hemisphere lit by oxygen, magnesium, aluminum and silicon atoms fluorescing in x-rays emitted by the Sun. The speckled sky records the “noise” of distant background X-ray sources, while the dark half of the Moon has a hint of illumination from Earth’s outermost atmosphere or geocorona that envelops the ROSAT observatory.



Gamma ray Moon


Gamma ray Moon
Gamma rays: Perhaps the most amazing image of all. If you could see the sky in gamma rays the Moon would be far brighter than the Sun as this dazzling image attempts to show. It was taken by the Energetic Gamma Ray Experiment Telescope (EGRET).  High-energy particles (mostly protons) from deep space called cosmic rays constantly bombard the Moon’s surface, stimulating the atoms in its crust to emit gamma rays. These create a unique high-energy form of “moonglow”.

Astronomy in the 21st century is like having a complete piano keyboard on which to play compared to barely an octave a century ago. The Moon is more fascinating than ever for it.



About 

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.
Posted by Nelio Inacio at 7:21 AM 0 comments

Thursday, January 1, 2015

Alexander Gerst’s Earth timelapses

Alexander Gerst’s Earth timelapses:






Original enclosures:
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Posted by Nelio Inacio at 6:04 AM 0 comments

Wednesday, December 31, 2014

Mercury Spacecraft’s 2015 Death Watch Could Go One More Month

Mercury Spacecraft’s 2015 Death Watch Could Go One More Month:



Artist's impression of the MESSENGER spacecraft, with Mercury in the background. Credit: JHUAPL


Artist’s impression of the MESSENGER spacecraft, with Mercury in the background. Credit: JHUAPL
If all goes well — and there’s no guarantee of this — NASA’s venerable Mercury sentinel may have an extra month of life left in it before it goes on a death plunge to the planet’s surface. Managers think they have found a way to stretch its fuel to allow the spacecraft to fly until April, measuring the planet’s magnetic field before falling forever.

Success will partially depend on a maneuver that will take place on Jan. 21, when MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) will raise its minimum altitude. But moreover, pushing the impact back to April will be the first extended test of using helium as a propellant in hydrazine thrusters, components that were not actually designed to get this done. But the team says it is possible, albeit less efficiently.

“Typically, when … liquid propellant is completely exhausted, a spacecraft can no longer make adjustments to its trajectory,” stated Dan O’Shaughnessy, a mission systems engineer with the Johns Hopkins University Applied Physics Laboratory.

“However, gaseous helium was used to pressurize MESSENGER’s propellant tanks, and this gas can be exploited to continue to make small adjustments to the trajectory.”



A crater on Mercury at the edge of the larger Oskison crater located in the plains north of Caloris basin. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


A crater on Mercury at the edge of the larger Oskison crater located in the plains north of Caloris basin. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
However long the mission does end up lasting, MESSENGER has shown us some unexpected things about the planet that is closest to the Sun. Turns out that water ice likely lies in some of the shadowed craters on its surface. And that organics, which were possibly delivered to Earth via comets and asteroids, are also on Mercury.

Atmospheric changes have been seen in the tenuous gases surrounding Mercury, showing a definite influence from the nearby Sun. And even the magnetic field lines on the planet are influenced by charged particles from our closest star.

And with MESSENGER viewing the planet from close-up, NASA and Johns Hopkins hope to learn more about volcanic flows, how crater walls are structured, and other features that you can see on the airless planet. Despite a 10-year mission and more than three years orbiting Mercury, it’s clear from MESSENGER that there is so much more to learn.

Source: Johns Hopkins University Applied Physics Laboratory



About 

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.
Posted by Nelio Inacio at 9:41 AM 0 comments

End the Year with a Bang! See a Bright Supernova in Virgo

End the Year with a Bang! See a Bright Supernova in Virgo:



The bright supernova (at tick marks) in the galaxy NGC 4666 photographed on December 24, 2014. Credit: Gregor Krannich


The bright supernova (at tick marks) in the galaxy NGC 4666 photographed on December 24, 2014. The galaxy shines at magnitude 11.8 and looks like a sliver of milky light in a telescope. Credit: Gregor Krannich
A 14th magnitude supernova discovered in the spiral galaxy NGC 4666 earlier this month has recently brightened to 11th magnitude, making it not only the second brightest supernova of the year, but an easy find in an 8-inch or larger telescope. I made a special trip into the cold this morning for a look and saw it with ease in my 10-inch (25-cm) scope at low power at magnitude 11.9.

Before the Moon taints the dawn sky, you may want to bundle up and have a look, too. The charts below will help you get there.



NGC 4666 is also known as the Superwind Galaxy. Home to vigorous star formation, a combination of supernova explosions and strong winds from massive stars in the starburst region drives a vast outflow of gas from the galaxy into space, a so-called “superwind”. Credit: ESO/J. Dietrich


NGC 4666 is also known as the Superwind Galaxy. Home to vigorous star formation, a combination of supernova explosions and strong winds from massive stars in the starburst region drives a vast outflow of gas from the galaxy into space, called a “superwind”. Credit: ESO/J. Dietrich
With the temporary name ASASSN-14lp, this Type Ia supernova was snatched up by the catchy-titled “Assassin Project”, short for  Automated Sky Survey for SuperNovae (ASAS-SN) on December 9th. Only 80 million light years from Earth, NGC 4666 is a relatively nearby spiral galaxy famous enough to earn a nickname.



Extra-planar soft X-ray emitting hot gas is observed above the most actively star-forming regions in the galactic disk of NGC 4666 and coexists together with filaments of the warm ionized medium, cosmic rays and vertical magnetic field structures channelling (or following) the outflow. Credit: M. Ehle and ESO


Hot, X-ray emitting gas in NGC 4666 billows around the main galaxy as a superwind seen here as outflows on either side of the optical image. Photo taken with the XMM-Newton telescope.  Credit: M. Ehle and ESO
Called the Superwind Galaxy, it’s home to waves of intense star formation thought to be caused by gravitational interactions between it and its neighboring galaxies, including NGC 4668, visible in the lower left corner of the photo above.

Supernovae also play a part in powering the wind which emerges from the galaxy’s central regions like pseudopods on an amoeba.  X-ray and radio light show the outflows best. How fitting that a bright supernova should happen to appear at this time. Seeing one of the key players behind the superwind with our own eyes gives us a visceral feel for the nature of its home galaxy.



Wide view map showing the location of the galaxy NGC 4666 in Virgo not far from Porrima or Gamma Virginis. This map shows the sky facing south shortly before the start of dawn in early January. Source: Stellarium


“Big picture” map showing the location of the galaxy NGC 4666 in Virgo not far from Porrima. The view faces south shortly before the start of dawn in early January. Source: Stellarium
Spectra taken of ASASSN-14lp show it to be a Type Ia object involving the explosive burning of a white dwarf star in a binary system. The Earth-size dwarf packs the gravitational might of a sun-size star and pulls hydrogen gas from the nearby companion down to its surface. Slowly, the dwarf gets heavier and more massive.

When it attains a mass 1.4 times that of the sun, it can no longer support itself. The star suddenly collapses, heats to incredible temperatures and burns up explosively in a runaway fusion reaction. Bang! A supernova.



Detailed map with stars to about magnitude 10. The galaxy is just a little more than a degree northeast of Porrima (Gamma Virginis). Source: Stellarium


Detailed map with stars to about magnitude 10. The galaxy is just a little more than a degree northeast of Porrima (Gamma Virginis). Source: Stellarium
Here are a couple maps to help you find the new object. Fortunately, it’s high in the sky just before the start of dawn in the “Y” of Virgo only a degree or so from the 3rd magnitude double star Porrima, also known as Gamma Virginis. Have at it and let us know if you spot the latest superwind-maker.

For more photos and magnitude updates, check out Dave Bishop’s page on the supernova. You can also print a chart with comparison magnitudes by clicking over to the AAVSO and typing in ASASSN-14lp in the “name” box.



About 

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.
Posted by Nelio Inacio at 9:41 AM 0 comments

Where Did Europa’s Water Geyser Go? Hubble Double-Checking Its Work

Where Did Europa’s Water Geyser Go? Hubble Double-Checking Its Work:



Rendering showing the location and size of water vapor plumes coming from Europa's south pole. Credit: NASA/ESA/L. Roth/SWRI/University of Cologne


Rendering showing the location and size of water vapor plumes coming from Europa’s south pole. Credit: NASA/ESA/L. Roth/SWRI/University of Cologne
It was about this time last year that Europa really began to excite us again. Following a sci-fi movie about the Jupiter moon, astronomers using the Hubble Space Telescope announced they had found possible water vapor near the icy moon — maybe from geysers erupting from its icy surface. (That is, if the finding was not due to signal noise, which researchers acknowledged at the time.)

As NASA ramped up (distant) plans to get close to Europa again, scientists began plumbing data from the Cassini spacecraft to see if its glance at the moon circa 2001 revealed anything. Turns out that the spacecraft didn’t see any sign of a plume. Which leads to the greater question, what is happening?

Now scientists are scurrying for a second look. Hubble is in the midst of a six-month search of the moon (from afar) to see if any more of the plumes are showing up. Now the theory is that the plumes, if they do exist, would be intermittent — at least, that’s according to the team looking at data from Cassini’s ultraviolet imaging spectograph (UVIS).



Europa (bottom left) in orbit around its planet, Jupiter, as spotted from the Cassini spacecraft in 2000. Credit: NASA/JPL/University of Arizona


Europa (bottom left) in orbit around its planet, Jupiter, as spotted from the Cassini spacecraft in 2000. Credit: NASA/JPL/University of Arizona
“It is certainly still possible that plume activity occurs, but that it is infrequent or the plumes are smaller than we see at Enceladus,” stated co-author Amanda Hendrix, a Cassini UVIS team member with the Planetary Science Institute in Pasadena. “If eruptive activity was occurring at the time of Cassini’s flyby, it was at a level too low to be detectable by UVIS.”

This finding was part of a greater set of observations showing that it’s not really Europa that is contributing plasma (superheated gas) to space — it’s the ultra-volcanic moon Io. And Europa itself is sending out 40 times less oxygen than previously believed to the area surrounding the moon.

“A downward revision in the amount of oxygen Europa pumps into the environment around Jupiter would make it less likely that the moon is regularly venting plumes of water vapor high into orbit, especially at the time the data was acquired,” NASA stated. This would stand in contrast to, say, Saturn’s Enceladus — which Cassini has seen sending plumes high above the moon’s surface.

The findings were presented at the American Geophysical Union meeting earlier this month and also published in the Astrophysical Journal. The research was led by Don Shemansky, a Cassini UVIS team member with Space Environment Technologies.

Source: Jet Propulsion Laboratory



About 

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.
Posted by Nelio Inacio at 9:40 AM 0 comments

Asteroids Don’t Break Up Like You Think They Do: Study

Asteroids Don’t Break Up Like You Think They Do: Study:



Artist's impression of an asteroid breaking up. Credit: NASA/JPL-Caltech


Artist’s impression of an asteroid breaking up. Credit: NASA/JPL-Caltech
The early Solar System was a shooting gallery. Smaller-body collisions happened far more frequently than we see it today, pockmarking the Moon and Mercury. On a larger scale, simulation show the Earth came close to blowing apart when a Mars-sized object crashed into us long ago.

So we’d be forgiven for thinking that it’s asteroid collisions that cause these tiny bodies to break up, given their numbers and the history of our neighborhood. But it turns out, a new study says, that the larger asteroids likely have another way of coming apart.

“For asteroids about 100 meters [328 feet] in diameter collisions are not the primarily cause of break ups – rapid rotation is,” the Smithsonian Astrophysical Observatory stated.

“Moreover, because the rate of collisions depends on the numbers and sizes of objects but rotation does not, their results are in strong disagreement with previous models of collisionally-produced small asteroids.”



Most near-Earth asteroids fall into three classes named after the first asteroid discovered in that class. Apollo and Aten asteroids cross Earth's orbit; Amors orbit just beyond Earth but cross Mars' orbit. Credit: Wikipedia


Most near-Earth asteroids fall into three classes named after the first asteroid discovered in that class. Apollo and Aten asteroids cross Earth’s orbit; Amors orbit just beyond Earth but cross Mars’ orbit. Credit: Wikipedia
It turns out that rotation has a strong effect on such a small body. First, the asteroid is emitting stuff that can produce a spin — water evaporating, or its surface expanding as heat from the Sun strikes it. Also, the Sun’s pressure on the asteroid creates a rotation. Between these different effects, at the right (or wrong) moment it can cause a catastrophic breakup.

As a simulation (coupled with observations from the Pan-STARRS telescope), the research is not done with complete certainty. But the model shows 90% confidence that asteroids in the so-called “main belt” (between Mars and Jupiter”) experience disruptions in this way, at least once per year.

The research was published in the journal Icarus and is also available in preprint version on Arxiv. It was led by Larry Denneau at the University of Hawaii.

Source: Smithsonian Astrophysical Observatory



About 

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.
Posted by Nelio Inacio at 9:38 AM 0 comments

Tuesday, December 30, 2014

Work Those Quads: Our Guide to the 2015 Quadrantid Meteors

Work Those Quads: Our Guide to the 2015 Quadrantid Meteors:



Don't fear the moonlight... Credit and copyright: John Chumack.


Don’t fear the moonlight… Quads were still visible along with the Moon from the Chumack observatory in 2012! Credit and copyright: John Chumack.
Quick… what’s the only major meteor shower named after a defunct constellation?  If you said the January Quadrantids, you’d be correct, as this often elusive but abrupt meteor shower is set to peak this coming weekend early in 2015.

And we do mean early, as in the night of January 3rd going into the morning of January 4th. This is a bonus, as early January means long dark nights for northern hemisphere observers. But the 2015 Quadrantids also has two strikes going against them however: first, the Moon reaches Full just a day later on January 5th, and second, January also means higher than average prospects for cloud cover (and of course, frigid temps!) for North American observers.



Jan 4th 3AM local. Starry Night Education Software.


The rising radiant of the Quads on the morning of January 4th at 3AM local. Note that the Moon and Jupiter are on the scene as well. Created using Starry Night Education software.
Don’t despair, however. In meteor shower observing as in hockey, you miss 100% of the shots that you don’t take.

Sorry for the sports analogy. The radiant for the Quadrantids is located in the modern day constellation of Draco near the Hercules-Boötes border at a right ascension 15 hours, 18 minutes and declination +49.5 degrees north. This puts it very near the +3.3 magnitude star Iota Draconis (Edasich).



Quads 2UT. Credit: Orbitron


The orientation of the Earth’s shadow at the predicted peak of the Quads on January 4th,  2:00 UT. Credit: Orbitron.
In 2015, bets are on for the Quadrantids to peak centered on 2:00 UT January 4th (9:00 PM EST on the 3rd), favoring northern Europe pre-dawn. The duration for the Quadrantids is short lived, with an elevated rate approaching 100 per hour lasting only six hours in duration. Keep in mind, of course, that it’ll be worth starting your vigil on Saturday morning January 3rd in the event that the “Quads” kick off early! I definitely wouldn’t pass up on an early clear morning on the 3rd, just in case skies are overcast on the morning of the 4th…

Due to their high northern radiant, the Quadrantids are best from high northern latitudes and virtually invisible down south of the equator.  Keep in mind that several other meteor showers are active in early January, and you may just spy a lingering late season Geminid or Ursid ‘photobomber’ as well among the background sporadics.



Photo by author


Avast: ye ole Mural Quadrant spied at the Columbia River Maritime Museum in Astoria, Oregon. Photo by author.
Moonset on the morning of the 4th occurs around 6 AM local, giving observers a slim one hour moonless window as dawn approaches. Blocking the Moon out behind a building or hill when selecting your observing site will aid you in your Quadrantid quest.



Stellarium


The approximate realm of the “Mural Quadrant” overlaid on modern day constellations. Credit Stellarium.
Antonio Brucalassi made the first historical reference to the Quadrantids, noting that “the atmosphere was traversed by… falling stars” on the morning of January 2nd, 1825. It’s interesting to note that the modern day peak for the Quads has now drifted a few days to the fourth, due mostly to the leap year-induced vagaries of our Gregorian calendar. The early January meteor shower was noted throughout the 19th century, and managed to grab its name from the trendy 19th century constellation of Quadrans Muralis, or the Mural Quadrant. Hey, we’re lucky that other also-rans, such as Lumbricus the ‘Earthworm’ and Officina Typograhica the ‘Printing Office’ fell to the wayside when the International Astronomical Union formalized the modern 88 constellations in 1922. Today, we know that the Quadrantids come from 2003 EH1, which is thought to be an extinct comet now trapped in the inner solar system on a high inclination, 5.5 year orbit. Could 2003 EH1 be related to the Great Comet of 1490, as some suggest? The enigmatic object reached perihelion in March of 2014, another plus in the positive column for the 2015 Quads.



What the heck is a Mural Quadrant?


What the heck is a Mural Quadrant? Like everything he did, Tycho Brahe super-sized his quadrant, depicted here. Credit: Wikimedia Commons.
Previous years for the Quadrantids have yielded the following Zenithal Hourly Rate (ZHR) maximums as per the International Meteor Organization:

2011= 90

2012= 83

2013= 137

2014= +200

The Quadrantid meteor stream has certainly undergone alterations over the years as a result of encounters with the planet Jupiter, and researchers have suggested that the shower may go the way of the 19th century Andromedids and become extinct entirely in the centuries to come.

Don’t let cold weather deter you, though be sure to bundle up, pour a hot toddy (or tea or coffee, as alcohol impacts the night vision) and keep a spare set of batteries in a warm pocket for that DSLR camera, as cold temps can kill battery packs quicker than you can say Custos Messium, the Harvest Keeper.

And though it may be teeth-chatteringly cold where you live this weekend, we actually reach our closest point to the Sun this Sunday, as Earth reaches perihelion on January 4th at around 8:00 UT, just 5 hours after the Quads are expected to peak. We’re just over 147 million kilometres from the Sun at perihelion, a 5 million kilometre difference from aphelion in July. Be thankful we live on a planet with a relatively circular orbit. Only Venus and Neptune beat us out in the true roundness department!

…and no, you CAN’T defy gravity around perihelion, despite the current ill conceived rumor going ‘round ye ole net…

And as a consolation prize to southern hemisphere observers, the International Space Station reaches a period of full illumination and makes multiple visible passes starting December 30th until January 3rd. This happens near every solstice, with the December season favoring the southern hemisphere, and June favoring the northern.



2003 Credit and Copyright: Frankie Lucena.


A 2003 south bound Quad nabbed from Cabo Rojo, Puerto Rico (Yes, that’s the Southern Cross!) Credit and Copyright: Frankie Lucena.
So don’t let the relatively bad prospects for the 2015 Quadrantids deter you: be vigilant, report those meteor counts to the IMO, send those meteor pics in to Universe Today and tweet those Quads to #Meteorwatch. Let’s “party like it’s 1899,” and get the namesake of an archaic and antiquated constellation trending!



About 

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.
Posted by Nelio Inacio at 9:05 AM 0 comments

Incredible Towering Structures Cast Shadows Across Saturn’s Rings

Incredible Towering Structures Cast Shadows Across Saturn’s Rings:



Vertical structures cause shadows on Saturn's B ring in this August 2009 picture from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute


Vertical structures cause shadows on Saturn’s B ring in this July 2009 picture from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
From a distance, Saturn’s rings look like a sheer sheet, but peer up close and you can see that impression is a mistake. Shadows from rubble believed to be two miles (3.2 kilometers) high are throwing shadows upon the planet’s B ring in this image from the Cassini spacecraft.

While the picture is from 2009, it caught the eye of the lead of the Cassini imaging team, who wrote eloquently about it in a blog post recently celebrating the link between wonder and the holidays.

“I have often thought: What a surreal sight this would be if you were flying low across the rings in a shuttle craft. To your eyes, the rings would seem like a gleaming white, scored, gravelly sheet below you, extending nearly to infinity,” wrote Carolyn Porco, the lead imager for the mission at the Cassini Imaging Central Laboratory for Operations (CICLOPS).

“And as you flew, you would see in the distance a wall of rubble that, eventually, as it neared, you would come to realize towered two miles above your head. There isn’t another sight like it in the Solar System!”



A 2007 artist impression of the aggregates of icy particles that form the 'solid' portions of Saturn's rings. These elongated clumps are continually forming and dispersing. The largest particles are a few metres across.They clump together to form elongated, curved aggregates, continually forming and dispersing. Credit: NASA/JPL/Univ. of Colorado


A 2007 artist impression of the aggregates of icy particles that form the ‘solid’ portions of Saturn’s rings. These elongated clumps are continually forming and dispersing. The largest particles are a few metres across.They clump together to form elongated, curved aggregates, continually forming and dispersing. Credit: NASA/JPL/Univ. of Colorado
Besides the inherent beauty and delicacy of this picture, another notable feature is how hard it is to capture. According to CICLOPS, one can only take this photo during Saturn’s equinox — once every 15 years in Earth time! That’s because the angle of the Sun’s light reaches the plane of the rings, allowing shadows to fall. The area itself is likely filled with moonlets of a kilometer (0.62 miles) in size.

“It is possible that these bodies significantly affect the ring material streaming past them and force the particles upward, in a ‘splashing’ manner,” the CICLOPS website notes.

We’ve included more pictures of Saturn’s rings below, all taken from the Cassini spacecraft. The machine is healthy and working hard after about 10.5 years working at the planet. One of its major tasks now is to observe changes in the planet and particularly its large moon, Titan, as the system nears the solstice.



Saturn's rings. Credit: NASA/JPL/Space Science Institute.


Saturn’s rings. Credit: NASA/JPL/Space Science Institute.


Enceladus and Tethys hang below Saturn's rings in this image from the Cassini spacecraft. Credit: NASA/JPL-Caltech/SS


Enceladus and Tethys hang below Saturn’s rings in this image from the Cassini spacecraft. Credit: NASA/JPL-Caltech/SS


Raw Cassini image of Titan and Enceladus backdropped by Saturn's rings. Image Credit: NASA/JPL/Space Science Institute


Raw Cassini image of Titan and Enceladus backdropped by Saturn’s rings. Image Credit: NASA/JPL/Space Science Institute


A close look at Enceladus, with Saturn's rings in the background. Credit: NASA/JPL/Space Science Institute


A close look at Enceladus, with Saturn’s rings in the background. Credit: NASA/JPL/Space Science Institute


The Cassini spacecraft looks close at Saturn to frame a view encompassing the entire C ring. Image credit: NASA/JPL/SSI


The Cassini spacecraft looks close at Saturn to frame a view encompassing the entire C ring. Image credit: NASA/JPL/SSI


Raw image of Saturn's rings. Credit: NASA/JPL/Space Science Institute


Raw image of Saturn’s rings. Credit: NASA/JPL/Space Science Institute


Rhea poses with Saturn's rings; Janus and Prometheus are off in the distance. Credit: NASA/JPL/Space Science Institute. Click for larger version


Rhea poses with Saturn’s rings; Janus and Prometheus are off in the distance. Credit: NASA/JPL/Space Science Institute. Click for larger version


Spokes visible in Saturn's B ring. Credit: NASA/JPL/Space Science Institute


Spokes visible in Saturn’s B ring. Credit: NASA/JPL/Space Science Institute


Looming vertical structures, seen here for the first time and created by Saturn's moon Daphnis, rise above the planet's otherwise flat, thin disk of rings to cast long shadows in this Cassini image. Credit: CICLOPS


Looming vertical structures, seen here for the first time and created by Saturn’s moon Daphnis, rise above the planet’s otherwise flat, thin disk of rings to cast long shadows in this Cassini image. Credit: CICLOPS


About 

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.
Posted by Nelio Inacio at 6:46 AM 0 comments

Marvelous Moondance: Jupiter Satellites Caught Eclipsing And Transiting

Marvelous Moondance: Jupiter Satellites Caught Eclipsing And Transiting:

A Dec. 24, 2014 (EST) timelapse of Io transiting Jupiter. Credit: IKYLSP/Reddit
On Christmas Eve, as millions upon millions of people focused on wrapping gifts and getting ready for the holidays, an amateur astronomer gave a small gift to the world. The person turned a telescope and camera to Jupiter and caught volcanic Io going across the face of the gas giant. This happened just a few days after professional astronomers caught a rare eclipse involving that very same moon.

“I wish I had been able to go on for longer but Jupiter went behind the house just before the transit ended. The transit is 102 frames (306 captures in total, RGB separate). Seeing was rather poor and a small amount of dew formed resulting in reduced brightness and contrast in some parts of the GIF,” wrote Reddit user IKYLSP.

“Something rather interesting with this one is the brief appearance of Ganymede from behind the planet’s shadow just before it’s eclipsed by the planet. If you zoom in you can actually see it as a half-moon shape which is really awesome.”

Jupiter’s moon Europa passes in front of Io in this picture captured from the Gemini North observatory on Dec. 16, 2014. Credit: Gemini Observatory
Speaking of half-moons, check out another awesome animation of Io taken from the Gemini North observatory on Dec. 16. Here, you can see icy Europa passing in front of the volcanic moon from the telescope’s perspective. Here’s part of what the observatory wrote about the rare event:

Observations of Jupiter’s volcanically active moon Io, obtained that night as part of a program led by Katherine de Kleer of UC Berkeley to watch for volcanic outbursts, revealed an unusual event involving Io and another large jovian moon, Europa. According to de Kleer, the images captured an occultation event in which Europa briefly blocked some of the light from Io, “…giving Io a very un-Io-like appearance!” These sorts of events occur when we observe the moons’ orbits edge-on, and can occasionally view the moons passing in front of one another.
And below you can see individual frames from the eclipse.



Jupiter's Europa passes in front of fellow moon Io in this sequence of images taken from the Gemini North observatory Dec. 16, 2014. Credit: Gemini Observatory


Jupiter’s Europa passes in front of fellow moon Io in this sequence of images taken from the Gemini North observatory Dec. 16, 2014. Credit: Gemini Observatory


About 

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.
Posted by Nelio Inacio at 6:45 AM 0 comments
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