Distant Suns Astronomy App Giveaway

Comet C/2011 L4 PANSTARRS photographed with a 200mm telephoto lens over Bridgetown, Western Australia on March 10. Credit: Jim Gifford

Have you ever been out on a beautiful, starry night and wondered what it was you were seeing? Maybe you are walking your date home on an amazing, clear night and want to impress the heck out of her by comparing her eyes to the stars in Orion’s Belt; or her movements are as graceful as the swans in Cygnus. The Distant Suns app will help you locate these features in the night sky to back your romantic gestures with pure science.

The people at Distant Suns have been working hard to improve the features in this already cool app. The latest and greatest addition is the ability to track Comet PANSTARRS more easily. One of my favorite features of this app is the overlaying of the local landscape with the current features in the night sky. This really allows you to have a reference point for your stargazing in the future should you find yourself without your cell phone.

For the rest of this week until Sunday only, the Distant Suns App is available for half price. If that is still too rich for your blood, try to win one of 6 free copies that Universe Today and Distant Suns is offering to give away this week. With the days getting longer and the nights getting warmer, this is a really cool way to learn about the features of the night sky without the benefit of a telescope.

This Giveaway is now closed. Thank you for your interest!

In order to be entered into the giveaway drawing, just put your email address into the box at the bottom of this post (where it says “Enter the Giveaway”) before Monday, March 11, 2013. We’ll send you a confirmation email, so you’ll need to click that to be entered into the drawing.

About Distant Suns Astronomy App distantsunslogo
Features include:

  • Augmented Reality Viewing overlays the sky with the local landscape (iOS only)
  • What’s Up? Offers an overview of the evening’s sky
  • GPS and Compass aware
  • News ticker of up-to-date space and astronomy news
  • NASA’s Night Sky Network of local astronomical events
  • Over 300,000 planets, stars, galaxies, nebula and star clusters
  • Interactive tour of the solar system
  • Available for purchase at the App Store
  • Distant Suns Astronomy Apps are also available for Android, Kindle and Nook. For more information, please go to Distant Suns product page.

 

 

Evil Empire Beware: Gas Giant Planets are Hard to Destroy

Jupiter and its four planet-size moons, called the Galilean satellites photographed and assembled into a collage by NASA.

Last year, physicists worked out the plausibility of a fully functional (if not fictional) Death Star being able to destroy planets, and found that the Galactic Empire’s technological terror could indeed destroy Earth-like rocky planets, but a Jupiter-sized gas planet would be a tough challenge.

Now, real but theoretical modeling confirms that gas giants like Jupiter would be really hard to destroy by any means, including by stars that undergo periodic outbursts. Actual stars, that is, not Death Stars.

Alan Boss is a noted astrophysicist at the Carnegie Institution of Washington, Department of Terrestrial Magnetism, who likes to create three dimensional models of planetary systems. In his recent work, he created 3-D models to help understand the possible origins of Jupiter and Saturn, two gas giants in our Solar System.

He created different models of new stars, which are surrounded by rotating gas disks where planets are thought to form. His models were based on different theories of planetary formation, such as that planets could form from slowly growing ice and rock cores, followed by rapid accretion of gas from the surrounding disk, or that planets form from clumps of dense gas, which increase in mass and density, forming a gas giant planet in a single step.

What he found was, that regardless of how gas giant planets form, they should be able to survive periodic outbursts of mass transfer from the gas disk onto the young star. One model similar to our own Solar System was stable for more than 1,000 years, while another model containing planets similar to our Jupiter and Saturn was stable for more than 3,800 years. The models showed that these planets were able to avoid being forced to migrate inward to be swallowed by the growing proto-sun, or being tossed completely out of the planetary system by close encounters with each other.

“Gas giant planets, once formed, can be hard to destroy,” said Boss, “even during the energetic outbursts that young stars experience.”

Some Sun-like stars undergo these periodic outbursts which can last about 100 years. The Death Star, on the other hand — which according to Star Wars lore, is a moon-sized battle station designed to spread fear throughout the galaxy – uses short bursts of its hypermatter reactor superlaser. However, the Death Star’s main power reactor is said to have the energy output equal to several main-sequence stars. But to destroy a planet like Jupiter, all power from essential systems and life support would be required, which is not necessarily possible.

So, in all cases – real, theoretical and fictional — gas giants appear to be safe!

You can read the about the Death Star paper here (from physicists who apparently had some time on their hands) here, and read about Boss’s theoretical modeling of here.

Boss is the author of The Crowded Universe, a book on the likelihood of finding life and habitable planets outside of our Solar System, and Looking For Earths, about the race to find new solar systems.

The Death Star in Star Wars. Credit: Lucasfilm.
The Death Star in Star Wars. Credit: Lucasfilm.

Giant Ancient Impact Crater Confirmed in Iowa

3-D perspective map of the Decorah impact feature looking northward. (Credit: USGS/Adam Kiel graphic/Northeast Iowa RC&D).

A monster lurks under northeastern Iowa. That monster is in the form of a giant buried basin, the result of a meteorite impact in central North America over 470 million years ago.

A recent aerial survey conducted by the state of Minnesota Geological Survey and the United States Geological Survey (USGS) confirms the existence of an impact structure long suspected near the eastern edge of the town of Decorah, Iowa. The goal of the 60 day survey was a routine look at possible mineral and water resources in the region, but the confirmation of the crater was an added plus. Continue reading “Giant Ancient Impact Crater Confirmed in Iowa”

Rare Eclipsing Binary Stars Provide Refined Measurements in the Universe

The Large Magellanic Cloud, a neighboring galaxy to the Milky Way. The positions of eight faint and rare cool eclipsing binary stars are marked with crosses. Credit: ESO/R. Gendler

Precise observations of a rare class of binary stars have now allowed a team of astronomers to improve the measurement of the distance to one of our neighboring galaxies, the Large Magellanic Cloud, and in the process, refine the Hubble Constant, an astronomical calculation that helps measure the expansion of the Universe. The astronomers say this is a crucial step towards understanding the nature of the mysterious dark energy that is causing the expansion to accelerate.

The team used telescopes at ESO’s La Silla Observatory in Chile, the Las Campanas Observatory also in Chile and two from the University of Hawaii at Manoa, and the Las Campanas Observatoryas well as others around the globe. These results appear in the 7 March 2013 issue of the journal Nature.

The new distance to the LMC is 163,000 light-years. The LMC is not the closest galaxy to the Milky Way; Canis Major Dwarf Galaxy, discovered in 2003 is considered the actual nearest neighbor at 42,000 light-years from the Galactic Center, and the Sagittarius Dwarf Elliptical Galaxy is about 50,000 light-years from the core of the Milky Way.

Astronomers ascertain the scale of the universe by first measuring the distances to close-by objects and then using them as standard candles — objects of known brightness — to pin down distances farther and farther out in the universe.

Up to now, finding an accurate distance to the LMC has proved elusive. Stars in that galaxy are used to fix the distance scale for more remote galaxies, so it is crucially important.

“This is a true milestone in modern astronomy. Because we know the distance to our nearest neighbor galaxy so precisely, we can now determine the rate at which the universe is expanding — the Hubble constant — with much better accuracy. This will allow us to investigate the physical nature of the enigmatic dark energy, the cause of the accelerated expansion of the universe,” says Dr. Rolf-Peter Kudritzki, an astronomer at the University of Hawaii’s Institute for Astronomy.

“For extragalactic astronomers,” said Dr. Fabio Bresolin, also from UH, “the distance to the Large Magellanic Cloud represents a fundamental yardstick with which the whole universe can be measured. Obtaining an accurate value for it has been a major challenge for generations of scientists. Our team has overcome the difficulties using an exquisitely accurate method, and is already working to cut the small remaining uncertainty by half in the next few years.”

The team worked out the distance to the LMC by observing rare close pairs of stars known as eclipsing binaries. As these stars orbit each other, they pass in front of each other. When this happens, as seen from Earth, the total brightness drops, both when one star passes in front of the other and, by a different amount, when it passes behind.

Read another recent article about studies that used eclipsing binaries to study the Light-travel-time Effect

By tracking these changes in brightness very carefully, and also measuring the stars’ orbital speeds, it is possible to work out how big the stars are, what their masses are, and other information about their orbits. When this is combined with careful measurements of the total brightness and colors of the stars, remarkably accurate distances can be found.

“Now we have solved this problem by demonstrably having a result accurate to 2%,” states Wolfgang Gieren (Universidad de Concepción, Chile) and one of the leaders of the team.

Sources: University of Hawaii, ESO

‘First Light’ Image for Telescope on the International Space Station

The first light from the new ISERV camera system, taken on February 16, 2013 shows the Rio San Pablo as it empties into the Golfo de Montijo in Veraguas, Panama. NASA image by Burgess Howell, SERVIR Global program.

As we reported in January, a new telescope was installed on the International Space Station – not to observe the stars, but instead look back to Earth to acquire imagery of specific areas of the world for disaster analysis and environmental studies. Called ISERV (International Space Station SERVIR Environmental Research and Visualization System), it has now taken its first image. Above is the “first light” from the new ISERV, taken at 1:44 p.m. local time on February 16, 2013.

No, this is not a giant tree trunk! It is the Rio San Pablo as it empties into the Golfo de Montijo in Veraguas, Panama.


The telescope is a modified off-the-shelf Celestron telescope, the Celestron CPC 925, a 9.25? diffraction limited Schmidt-Cassegrain telescope and if you were to buy a un-modified version, it would cost $2,500 including the mount.

The ISERV version was modified at the Marshall Space Flight Center, which is where it is controlled from, as well. It is installed in the Window Observational Research Facility (WORF) in the station’s Destiny laboratory. With a resolution down to 3.2 meters (10 feet), it will be possible to spot fairly small details and objects.

Canadian astronaut Chris Hadfield with the new ISERV (International Space Station SERVIR Environmental Research and Visualization System), a modified Celestron telescope for Earth observation. Credit: NASA/CSA
Canadian astronaut Chris Hadfield with the new ISERV (International Space Station SERVIR Environmental Research and Visualization System), a modified Celestron telescope for Earth observation. Credit: NASA/CSA

This ISERV Pathfinder is intended as an engineering exercise, with the long-term goal of developing a system for providing imagery to developing nations as they monitor natural disasters and environmental concerns.

“ISERV’s full potential is yet to be seen, but we hope it will really make a difference in people’s lives,” said principal investigator Burgess Howell of NASA’s Marshall Space Flight Center. “For example, if an earthen dam gives way in Bhutan, we want to be able to show officials where the bridge is out or where a road is washed out or a power substation is inundated. This kind of information is critical to focus and speed rescue efforts.”

The system will use on positioning software to know where the space station is at each moment and to calculate the next chance to view a particular area on the ground. If there’s a good viewing opportunity, the SERVIR team will instruct the camera to take high-resolution photographs at 3 to 7 frames per second, totaling as many as 100 images per pass.

The current mission will test the limitations of this ISERV system and identify measures for improvements in a more permanent system. For instance, the engineering team is working to determine how the geometry of the ISS window affects the imagery; how much sunlight is needed to capture clear images; and how the atmosphere affects that clarity. This characterization phase will last several weeks to a few months. Eventually, ISERV should be made available to the natural hazards community and to basic research scientists.

Source: NASA Earth Observatory

Next Soyuz Crew Will Take 6-Hour Fast-Track to Space Station

Russian Soyuz spacecraft, docked to the International Space Station. Credit: NASA.

The next Soyuz crew will be the first to try out the new abbreviated four-orbit rendezvous with the International Space Station. This relatively new, modified launch and docking profile for the Russian ships has been tried successfully with three Progress resupply vehicles, and now Roscosmos and NASA have agreed to try it on a human flight.

“We tried this approach on the cargo vehicles, and now we will try to do it on the manned vehicles,” said Sergei Krikalev, former cosmonaut, who now leads the Gagarin Cosmonaut Training Center near Moscow, speaking through an interpreter on NASA TV. “Now we have onboard new machinery and new software, so the vehicle is more autonomous, so it’s possible to do a lot onboard the vehicle and to calculate the burns so they don’t consume a lot of fuel.”

In the past, Soyuz manned capsules and Progress supply ships were launched on trajectories that required about two days, or 34 orbits, to reach the ISS. The new fast-track trajectory has the rocket launching shortly after the ISS passes overhead. Then, additional firings of the vehicle’s thrusters early in its mission expedites the time required for a Russian vehicle to reach the Station.

Liftoff of the Soyuz TMA-08M spacecraft is scheduled for 4:43 p.m. EDT (20:43 UTC) on March 28 from the Baikonur Cosmodrome in Kazakhstan. Docking is set for 10:31 p.m. EDT (02:31 UTC).

“The Soyuz is not the most comfortable vehicle to be in for an extended period of time,” said NASA astronaut Chris Cassidy who is part of the Expedition 35/36 crew who will make the first fast-track flight. “The toilet is right next to where you sleep which are right next to your buddy and eating and all; it’s like living for a day in a smart car or a Volkswagen Beetle….So the benefit to us is we get to the space station faster with the facilities that it offers, much more comfortable type of environment to be in and it also demonstrates some technology that’s useful in getting to the space station on that same day.”

One of the reasons given in the past for having the two-day or even three-day flight in the Soyuz was to allow the crew members time to get acclimated to being in a weightless environment. This new fast approach doesn’t allow for that, but Cassidy said he doesn’t think that thinking is really applicable, since the cramped Soyuz is so different from the voluminous space station.

“The adaptation of that I think is a little bit different,” he said. “You’re really not truly adapting in that day and a half. Two days on the Soyuz, that same adaptation that you’ll have once you get to the space station just because it’s a different perspective for your brain to get its arms around.”

The Soyuz took the first crew to the International Space Station in November 2000, and since that time, at least one Soyuz has always been at the Station, generally to bring the crews back and forth, but also to serve as a lifeboat should the crew have to return to Earth unexpectedly. Now that the space shuttles have been retired, the Soyuz is currently the only way for ISS crews to go to and from the Station. When there is a full crew of six on board, that means two Soyuz are docked at the ISS.

SpaceX is shooting for sometime in 2015 for the first crew flights of the Dragon to the ISS.

Black Holes, Fermi Bubbles and the Milky Way

Deep at the heart of our galaxy lurks a black hole. This isn’t exciting news, but neither is it a very exciting place. Or is it? While all might be quiet on the western front now, there may be evidence that our galactic center was once home to some pretty impressive activity – activity which may have included multiple collision events and mergers of black holes as it gorged on a satellite galaxies. Thanks to new insights from a pair of assistant professors, Kelly Holley-Bockelmann at Vanderbilt and Tamara Bogdanovic at Georgia Institute of Technology, we have more evidence which points to the Milky Way’s incredibly active past.

“Tamara and I had just attended an astronomy conference in Aspen, Colorado, where several of these new observations were announced,” said Holley-Bockelmann. “It was January 2010 and a snow storm had closed the airport. We decided to rent a car to drive to Denver. As we drove through the storm, we pieced together the clues from the conference and realized that a single catastrophic event – the collision between two black holes about 10 million years ago – could explain all the new evidence.”

Now, imagine a night sky illuminated by a a huge nebula, one that covers half the celestial sphere. This isn’t a dream, it’s a reality. These massive lobes of high-energy radiation are known as Fermi bubbles and they cover a region some 30,000 light years on either side of the Milky Way’s core. While we can’t observe them directly in visible light, these particles are moving along at close to 186,000 miles per second and glowing in x-ray and gamma ray wavelengths.

According to Fulai Guo and William G. Mathews of the University of California at Santa Cruz: “The Fermi bubbles provide plausible evidence for a recent powerful AGN jet activity in our Galaxy, shedding new insights into the origin of the halo CR population and the channel through which massive black holes in disk galaxies release feedback energy during their growth.”

However, our galactic center is home to more than just some incredible bubbles – it’s the location of three of the most massive clusters of young stars within the Milky Way’s realm. Known as the Central, Arches and Quintuplet clusters, each grouping houses several hundred hot, young stars which dwarf the Sun. They will live short, bright, violent lives… burning out in a scant few million years. Because they live fast and die young, these cluster stars must have formed within recent years during a eruption of star formation near the galactic center – another clue to this cosmic puzzle.

“Because of their high mass, and apparent top-heavy IMF, the Galactic Center clusters contain some of the most massive stars in the Galaxy. This is important, as massive stars are key ingredients and probes of astrophysical phenomena on all size and distance scales, from individual star formation sites, such as Orion, to the early Universe during the age of reionization when the first stars were born. As ingredients, they control the dynamical and chemical evolution of their local environs and individual galaxies through their influence on the energetics and composition of the interstellar medium.” says Donald F. Figer. “They likely play an important role in the early evolution of the first galaxies, and there is evidence that they are the progenitors of the most energetic explosions in the Universe, seen as gamma ray bursts. As probes, they define the upper limits of the star formation process and their presence likely ends further formation of nearby lower mass stars. They are also prominent output products of galactic mergers, starburst galaxies, and active galactic nuclei.”

To deepen the mystery, take a closer look at our central black hole. It spans about 40 light seconds in diameter and weighs about four million solar masses. According to what we know, this should produce intensive gravitational tides – ones that should be sucking in the surroundings. So how is it that astronomers have uncovered groups of new, bright stars closer than 3 light years from the event horizon? Of course, they could be on their way to oblivion, but the data shows these stars seem to have formed there. That’s quite a feat considering it would require a molecular cloud 10,000 times more dense than the one located at our galactic center! Shouldn’t there also be old stars located there as well? The answer is yes, there should be… but there are far fewer than what we can observe and what current theoretical models predict.

Holley-Bockelmann wasn’t about to let the problem rest. When she returned home, she enlisted the aid of Vanderbilt graduate student Meagan Lang to help solve the riddle. Then they recruited Pau Amaro-Seoane from the Max Planck Institute for Gravitational Physics in Germany, Alberto Sesana from the Institut de Ciències de l’Espai in Spain, and Vanderbilt Research Assistant Professor Manodeep Sinha to help. With so many bright minds to help solve this riddle, they soon arrived at a plausible explanation – one which matches observations and allows for testable predictions.

According to their theory, a Milky Way satellite galaxy began migrating towards our core. As it merged with our galaxy, its mass was torn away, leaving only its black hole and a small collection of gravitationally bound stars. After several million years, this “leftover” eventually reached the galactic center and the black holes began to merge. As the smaller black hole was swirled around the larger, it plowed up huge furrows of gas and dust, pushing it into the larger black hole and created the Fermi bubbles. The dueling gravitational forces weren’t gentle… these intense tides were quite capable of compressing the molecular clouds surrounding the core into the density required to produce fresh, young stars. Perhaps the very young stars we now observe at the galactic center?

However, there’s more to the picture than meets the eye. This same plowing of the cosmic turf would have also pushed out existing older stars from the vicinity of the massive central black hole. It’s a scene which fits current models where a black hole merger flings stars out into the galaxy at hyper velocities… a scene which fits the observation of a lack of old stars at the boundaries of our supermassive black hole.

“The gravitational pull of the satellite galaxy’s black hole could have carved nearly 1,000 stars out of the galactic centre,” said Bogdanovic. “Those stars should still be racing through space, about 10,000 light years away from their original orbits.”

Can any of this be proved? The answer is yes. Thanks to large scale surveys like the Sloan Digital Sky Survey, we should be able to pinpoint stars moving at a higher velocity than stars which haven’t been subjected to a similar interaction. If astronomers like Holley-Bockelmann and Bogdanovic look at the hard evidence, they are likely to discover a credible number of high velocity stars which will validate their Milky Way merger model.

Or are they just blowing bubbles?

Evidence for a Deep Ocean on Europa Might be Found on its Surface

Astronomers hypothesize that chloride salts bubble up from the icy moon's global liquid ocean and reach the frozen surface where they are bombarded with sulfur from volcanoes on Jupiter's largest moon, Io. This illustration of Europa (foreground), Jupiter (right) and Io (middle) is an artist's concept. Credit: Keck Observatory.

Astronomer Mike Brown and his colleague Kevin Hand might be suffering from “Pump Handle Phobia,” as radio personality Garrison Keillor calls it, where those afflicted just can’t resist putting their tongues on something frozen to see if it will stick. But Brown and Hand are doing it all in the name of science, and they may have found the best evidence yet that Europa has a liquid water ocean beneath its icy surface. Better yet, that vast subsurface ocean may actually shoot up to Europa’s surface, on occasion.

In a recent blog post, Brown pondered what it would taste like if he could lick the icy surface of Jupiter’s moon Europa. “The answer may be that it would taste a lot like that last mouthful of water that you accidentally drank when you were swimming at the beach on your last vacation. Just don’t take too long of a taste. At nearly 300 degrees (F) below zero your tongue will stick fast.”

His ponderings were based on a new paper by Brown and Hand which combined data from the Galileo mission (1989 to 2003) to study Jupiter and its moons, along with new spectroscopy data from the 10-meter Keck II telescope in Hawaii.

The study suggests there is a chemical exchange between the ocean and surface, making the ocean a richer chemical environment.

“We now have evidence that Europa’s ocean is not isolated—that the ocean and the surface talk to each other and exchange chemicals,” said Brown, who is an astronomer and professor of planetary astronomy at Caltech. “That means that energy might be going into the ocean, which is important in terms of the possibilities for life there. It also means that if you’d like to know what’s in the ocean, you can just go to the surface and scrape some off.”

“The surface ice is providing us a window into that potentially habitable ocean below,” said Hand, deputy chief scientist for solar system exploration at JPL.

Europa’s ocean is thought to cover the moon’s whole globe and is about 100 kilometers (60 miles) thick under a thin ice shell. Since the days of NASA’s Voyager and Galileo missions, scientists have debated the composition of Europa’s surface.

Salts were detected in the Galileo data – “Not ‘salt’ as in the sodium chloride of your table salt,” Brown wrote in his blog, “Mike Brown’s Planets,” “but more generically ‘salts’ as in ‘things that dissolve in water and stick around when the water evaporates.’”

That idea was enticing, Brown said, because if the surface is covered by things that dissolve in water, that strongly implies that Europa’s ocean water has flowed on the surface, evaporated, and left behind salts.

But there were other explanations for the Galileo data, as Europa is constantly bombarded by sulfur from the volcanoes on Io, and the spectrograph that was on the Galileo spacecraft wasn’t able to tell the difference between salts and sulfuric acid.

But now, with data from the Keck Observatory, Brown and Hand have identified a spectroscopic feature on Europa’s surface that indicates the presence of a magnesium sulfate salt, a mineral called epsomite, that could have formed by oxidation of a mineral likely originating from the ocean below.

This view of Jupiter's moon Europa features several regional-resolution mosaics overlaid on a lower resolution global view for context. The regional views were obtained during several different flybys of the moon by NASA's Galileo mission.  Image credit: NASA/JPL-Caltech/University of Arizona.
This view of Jupiter’s moon Europa features several regional-resolution mosaics overlaid on a lower resolution global view for context. The regional views were obtained during several different flybys of the moon by NASA’s Galileo mission. Image credit: NASA/JPL-Caltech/University of Arizona.

Brown and Hand started by mapping the distribution of pure water ice versus anything else. The spectra showed that even Europa’s leading hemisphere contains significant amounts of non-water ice. Then, at low latitudes on the trailing hemisphere — the area with the greatest concentration of the non-water ice material — they found a tiny, never-before-detected dip in the spectrum.

The two researchers tested everything from sodium chloride to Drano in Hand’s lab at JPL, where he tries to simulate the environments found on various icy worlds. At the end of the day, the signature of magnesium sulfate persisted.

The magnesium sulfate appears to be generated by the irradiation of sulfur ejected from the Jovian moon Io and, the authors deduce, magnesium chloride salt originating from Europa’s ocean. Chlorides such as sodium and potassium chlorides, which are expected to be on the Europa surface, are in general not detectable because they have no clear infrared spectral features. But magnesium sulfate is detectable. The authors believe the composition of Europa’s ocean may closely resemble the salty ocean of Earth.

While no one is going to be traveling to Europa to lick its surface, for now, astronomers will continue to use the modern giant telescopes on Earth to continue to “take spectral fingerprints of increasing detail to finally understand the mysterious details of the salty ocean beneath the ice shell of Europa,” Brown said.

Also, NASA is looking into options to explore Europa further. (Universe Today likes the idea of a big drill or submarine!)

But in the meantime what happens next? “We look for chlorine, I think,” Brown wrote. “The existence of chlorine as one of the main components of the non-water-ice surface of Europa is the strongest prediction that this hypothesis makes. We have some ideas on how we might look; we’re working on them now. Stay tuned.”

Read Brown & Hand’s paper.

Sources: Mike Brown’s Planets, Keck Observatory, JPL

Update on the Comet that Might Hit Mars

Simulation of the close approach of C/2013 A1 to Mars in Celestia using info from the Minor Planet Center. Credit: Ian Musgrave/Astroblog.

The latest trajectory of comet 2013 A1 (Siding Spring) generated by the Near-Earth Object Program Office at the Jet Propulsion Laboratory indicates the comet will pass within 186,000 miles (300,000 kilometers) of Mars in October of 2014, and there is a strong possibility that it might pass much closer. The NEO Program Office’s current estimate based on observations through March 1, 2013, has it passing about 31,000 miles (50,000 kilometers) from the Red Planet’s surface. That distance is about two-and-a-half times that of the orbit of outermost moon, Deimos.

Previous estimates put it on a possible collision course with Mars.

This video, above, is based on comet’s orbit calculated by Leonid Elenin, which has it is coming within 58,000 km, and visualized by SpaceEngine software.

The trajectory for comet Siding Spring is being refined as more observations are made. Rob McNaught discovered this comet on Jan. 3, 2013, at Siding Spring Observatory in Australia, and looking back at archival observations has unearthed more images of the comet, extending the observation interval back to Oct. 4, 2012. Further refinement to its orbit is expected as more observational data is obtained.

“At present, Mars lies within the range of possible paths for the comet and the possibility of an impact cannot be excluded,” said an update today from JPL. “However, since the impact probability is currently less than one in 600, future observations are expected to provide data that will completely rule out a Mars impact.”

JPL’s update also outlined how during the close Mars approach, the comet will likely achieve a total visual magnitude of zero or brighter, as seen from Mars-based spacecraft. From Earth, the comet is not expected to reach naked eye brightness, but it may become bright enough (about magnitude 8) that it could be viewed from the southern hemisphere in mid-September 2014, using binoculars, or small telescopes.

Siding Spring likely originated from the Oort cloud. Amateur and professional astronomers will be keeping an eye on this comet’s trajectory to determine if it will end up hitting Mars or not.

Source: JPL

Comet PANSTARRS Crosses Paths With Zodiacal Light

The tapering wedge of the zodiacal light reaches from the western horizon on March 3, 2013 toward the bright Planet Jupiter at top. Credit: Bob King

With the much-anticipated PANSTARRS comet emerging into the evening sky this week, we might keep our eyes open to another sight happening at nearly the same time. If you live where the sky to the west is very dark, look for the zodiacal light, a tapering cone of softly-luminous light slanting up from the western horizon toward the bright planet Jupiter near twilight’s end.

It makes its first appearance about 75 minutes after sunset and lingers for an hour and a half. Sunlight reflected from countless dust particles shed by comets and to a lesser degree by colliding asteroids is responsible for this little-noticed phenomenon. Comets orbiting approximately in the plane of the solar system between Jupiter and the sun are its key contributors. Jupiter’s gravity stirs the works into a pancake-like cloud that permeates the inner solar system.

The zodiacal is formed of dust left behind by comets orbiting between Jupiter and the sun and forms a pancake-like structure in the plane of the planets. Illustration: Bob King
The zodiacal is formed of dust left behind by comets orbiting between Jupiter and the sun and forms a pancake-like structure in the plane of the planets. Illustration: Bob King

More of us would be more aware of the zodiacal light if we knew better when and where to look. While a dark sky is essential, you don’t have to move to the Atacama Desert. I live 9 miles from a moderate-sized, light-polluted city; the western sky is terrible but the east is plenty dark and ideal for watching the morning zodiacal light in the fall months.

Near its base, the cone easily matches the summer Milky Way in brightness and spans about two fists held horizontally at arm’s length. At first glance you’d be tempted to think it was the lingering glow of twilight until you realize it’s nearly two hours after sunset. The farther you follow up the cone, the fainter and narrower it becomes. From top to bottom the light pyramid measures nearly five fists long. In other words, it’s HUGE.

The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky 90 minutes after sunset in early March facing west. Created with Stellarium
The pyramid-shaped zodiacal light cone is centered on the same path the sun and planets take across the sky called the ecliptic. This map shows the sky facing west 90 minutes after sunset in early March. Created with Stellarium

The zodiacal light is centered on the same path the sun and planets take through the sky called the ecliptic, an imaginary circle that runs through the familiar 12 constellations of the zodiac. Every spring, that path intersects the western horizon at dusk at a steep angle, tilting the light cone up into clear view. A similar situation happens in the eastern sky before dawn in October. Of course the light’s there all year long, but we don’t notice it because it’s slanted at a lower angle and blends into the hazy air near the horizon.

The zodiacal light we see at dusk is a portion of the larger zodiacal dust cloud that extends at least to Jupiter’s distance (~500 million miles) on either side of the Sun, making it the single biggest thing in the Solar System visible with the naked eye. Under exceptional skies, like those found on distant mountaintops or far from city lights, the cone tapers into the zodiacal band that completely encircles the sky.

The gegenschein is the small, oval glow within the zodiacal band seen in this photo taken at the European Southern Observatory in Chile. Credit: ESO / Yuri Beletsky
The gegenschein is the small, oval glow within the zodiacal band seen in this photo taken at the European Southern Observatory in Chile. Credit: ESO / Yuri Beletsky

Exactly opposite the sun around local midnight, you might see an enhancement in the band called the gegenschein (GAY-gen-shine). This eerie oval glow is caused by sunlight shining directly on interplanetary dust grains and then back to your eye. A similar boost happens for the same reason at the time of full moon.

Deep connections abound throughout the universe. Over time, much of the comet dust in the zodiacal cloud either spirals inward toward the sun or gets pushed outward by solar radiation. The fact that we can still see it today means it’s continually being replenished by the silent comings and goings of comets.

Comet C/2011 L4 PANSTARRS photographed with a 200mm telephoto lens over Bridgetown, Western Australia on March 3. Credit: Jim Gifford
Comet C/2011 L4 PANSTARRS photographed with a 200mm telephoto lens over Bridgetown, Western Australia on March 3.
Credit: Jim Gifford

Consider Comet L4 PANSTARRS. Dribs and drabs of dust sputtered from this comet during its current trip to the inner solar system may find their way into the zodiacal cloud to secure its presence for future sky watchers. How wonderful then the comet and the ghostly light should happen to be at their best the very same time of year.

Zodical light touching the Seven Sisters star cluster also known as the Pleiades March 19, 2012. Credit: Bob King
Zodical light touching the Seven Sisters star cluster also known as the Pleiades March 19, 2012. Credit: Bob King

Now through March 13 is the ideal time for zodiacal light viewing. If you begin your evening with Comet PANSTARRS, stick around until nightfall to spot the light. Face west and cast a wide view across the sky, sweeping your gaze from left to right and back again. Look for a big, hazy glow reaching from the horizon toward the Planet Jupiter. After the 13th, the waxing moon will wash out the subtle light cone for a time. Another “zodiacal window” opens up in late March through mid-April when the moon comes up too late to spoil the view.

As you take in the sight, consider how something as small as a dust mote, when teamed with its mates, can create a jaw-dropping comet’s tail, meet its end in the fiery finale of a meteor shower or span a billion miles of space.