A view of the crater Prokofiev on Mercury. The crater is the largest one on the planet's north pole area to have "radar-bright" material, a probable sign of ice. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.
New pictures of water ice at Mercury’s north pole — the first such optical images ever — could help scientists better understand how water came to planets in the rest of the Solar System, including Earth. The image you see above came courtesy of NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft.
Mercury is a hot planet (it’s the closest one to the Sun), so the only way the ice survives is in deep shadow. This makes it hard to spot unless scientists use some clever techniques. In this case, they examined some scattered light from Prokofiev, the biggest crater in Mercury’s north pole suspected to hold the deposits.
The pictures show that Prokofiev’s surface water ice likely arrived after the craters underneath. And in an intriguing find, there is probably other water ice sitting under dark materials believed to be “frozen organic-rich compounds,” stated the Johns Hopkins University Applied Physics Laboratory.
“This result was a little surprising, because sharp boundaries indicate that the volatile deposits at Mercury’s poles are geologically young, relative to the time scale for lateral mixing by impacts,” stated lead researcher Nancy Chabot, the Instrument Scientist for MESSENGER’s Mercury dual imaging system.
Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)
“One of the big questions we’ve been grappling with is ‘When did Mercury’s water ice deposits show up?’ Are they billions of years old, or were they emplaced only recently?”, added Chabot, who is a planetary scientist at the Johns Hopkins University Applied Physics Laboratory in Maryland. “Understanding the age of these deposits has implications for understanding the delivery of water to all the terrestrial planets, including Earth.”
Another intriguing property comes when scientists compare Mercury to the Moon: because the ice looks different on both relatively atmosphere-less bodies, scientists believe the water came more recently to the Moon. But more study is required.
Three views of an escaping atmosphere, obtained by MAVEN’s Imaging Ultraviolet Spectrograph. By observing all of the products of water and carbon dioxide breakdown, MAVEN's remote sensing team can characterize the processes that drive atmospheric loss on Mars.
Image Credit:
University of Colorado/NASA
It’s been less than a month since NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft slipped into orbit. But it’s already provided mission scientists their first look at Mars’ tenuous atmosphere.
“Everything is performing well so far,” said Bruce Jakosky, the mission’s principle investigator, in a news release. “All the instruments are showing data quality that is better than anticipated at this early stage of the mission. The spacecraft is performing beautifully. It’s turning out to be an easy and straightforward spacecraft to fly, at least so far. It really looks as if we’re headed for an exciting science mission.”
Data collected by MAVEN will answer a longstanding puzzle among planetary scientists. There’s ample evidence that early in the Red Planet’s history it had a much denser atmosphere. Rain fell from the sky and water carved its surface. But then the atmosphere vanished, and scientists are unsure why.
One leading theory is that the gas escaped to space, stripped away by the solar wind rushing past. (Click here to see a cool animation of that process.) Here on Earth, our magnetosphere helps protect our atmosphere from the solar wind. But once Mars lost its own magnetosphere, billions of years ago, its atmosphere became vulnerable.
MAVEN’s spectrometers will attempt to determine if hydrogen atoms, torn from water molecules by ultraviolet sunlight, are escaping to space and at what rate. Already, the spacecraft has observed the edges of the Martian atmosphere using its Imaging Ultraviolet Spectrograph (IUVS) camera, which is sensitive to the sunlight reflected by the atoms.
“With these observations, MAVEN’s IUVS has obtained the most complete picture of the extended Martian upper atmosphere ever made,” said team member Mike Chaffin from Colorado University at Boulder.
So far scientists have used IUVS to create a map of Mars’ ozone. “With these maps we have the kind of complete and simultaneous coverage of Mars that is usually only possible for Earth,” said team member Justin Deighan, also from CU-Boulder.
There will be about two weeks of additional instrument calibration and testing before MAVEN starts its primary science mission in early to mid-November. It will then likely take a few additional months to build up enough measurements to have a clear sense of what’s going on. But the initial results are promising.
An artists illustration of the early Universe. Image Credit: NASA
There’s nothing more out of this world than quasi-stellar objects or more simply – quasars. These are the most powerful and among the most distant objects in the Universe. At their center is a black hole with the mass of a million or more Suns. And these powerhouses are fairly compact – about the size of our Solar System. Understanding how they came to be and how — or if — they evolve into the galaxies that surround us today are some of the big questions driving astronomers.
Now, a new paper by Yue Shen and Luis C. Ho – “The diversity of quasars unified by accretion and orientation” in the journal Nature confirms the importance of a mathematical derivation by the famous astrophysicist Sir Arthur Eddington during the first half of the 20th Century, in understanding not just stars but the properties of quasars, too. Ironically, Eddington did not believe black holes existed, but now his derivation, the Eddington Luminosity, can be used more reliably to determine important properties of quasars across vast stretches of space and time.
A quasar is recognized as an accreting (meaning- matter falling upon) super massive black hole at the center of an “active galaxy”. Most known quasars exist at distances that place them very early in the Universe; the most distant is at 13.9 billion light years, a mere 770 million years after the Big Bang. Somehow, quasars and the nascent galaxies surrounding them evolved into the galaxies present in the Universe today. At their extreme distances, they are point-like, indistinguishable from a star except that the spectra of their light differ greatly from a star’s. Some would be as bright as our Sun if they were placed 33 light years away meaning that they are over a trillion times more luminous than our star.
An artists illustration of the central engine of a quasar. These “Quasi-stellar Objects” QSOs are now recognized as the super massive black holes at the center of emerging galaxies in the early Universe. (Photo Credit: NASA)
The Eddington luminosity defines the maximum luminosity that a star can exhibit that is in equilibrium; specifically, hydrostatic equilibrium. Extremely massive stars and black holes can exceed this limit but stars, to remain stable for long periods, are in hydrostatic equilibrium between their inward forces – gravity – and the outward electromagnetic forces. Such is the case of our star, the Sun, otherwise it would collapse or expand which in either case, would not have provided the stable source of light that has nourished life on Earth for billions of years.
Generally, scientific models often start simple, such as Bohr’s model of the hydrogen atom, and later observations can reveal intricacies that require more complex theory to explain, such as Quantum Mechanics for the atom. The Eddington luminosity and ratio could be compared to knowing the thermal efficiency and compression ratio of an internal combustion engine; by knowing such values, other properties follow.
Several other factors regarding the Eddington Luminosity are now known which are necessary to define the “modified Eddington luminosity” used today.
The new paper in Nature shows how the Eddington Luminosity helps understand the driving force behind the main sequence of quasars, and Shen and Ho call their work the missing definitive proof that quantifies the correlation of a quasar properties to a quasar’s Eddington ratio.
They used archival observational data to uncover the relationship between the strength of the optical Iron [Fe] and Oxygen[O III] emissions – strongly tied to the physical properties of the quasar’s central engine – a super-massive black hole, and the Eddington ratio. Their work provides the confidence and the correlations needed to move forward in our understanding of quasars and their relationship to the evolution of galaxies in the early Universe and up to our present epoch.
Astronomers have been studying quasars for a little over 50 years. Beginning in 1960, quasar discoveries began to accumulate but only through radio telescope observations. Then, a very accurate radio telescope measurement of Quasar 3C 273 was completed using a Lunar occultation. With this in hand, Dr. Maarten Schmidt of California Institute of Technology was able to identify the object in visible light using the 200 inch Palomar Telescope. Reviewing the strange spectral lines in its light, Schmidt reached the right conclusion that quasar spectra exhibit an extreme redshift and it was due to cosmological effects. The cosmological redshift of quasars meant that they are at a great distance from us in space and time. It also spelled the demise of the Steady-State theory of the Universe and gave further support to an expanding Universe that emanated from a singularity – the Big Bang.
Dr. Maarten Schmidt, Caltech, with Donald Lynden-Bell, were the first recipients of the Kavli Prize in Astrophysics, “for their seminal contributions to understanding the nature of quasars”. While in high school, this author had the privilege to meet Dr. Schmidt at the Los Angeles Museum of Natural History after his presentation to a group of students. (Photo Credit: Caltech)
The researchers, Yue Shen and Luis C. Ho are from the Institute for Astronomy and Astrophysics at Peking University working with the Carnegie Observatories, Pasadena, California.
Mosaic of OSIRIS images of landing site "J" on Comet 67P/CG. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
The long-awaited deployment of the Philae lander, currently “piggybacked” aboard ESA’s Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko, will occur in less than a month and we now have our best look yet at the area now green-lighted for touchdown. The picture above, made from two images acquired by Rosetta’s OSIRIS imaging instrument, shows a 500-meter circle centered on “Site J,” a spot on the comet’s “head” carefully chosen by mission scientists as the best place in which Philae should land, explore, and ultimately travel around the Sun for the rest of its days. And as of today, it’s a GO!
Site J was selected from among five other possible sites and was chosen because of the relative safety of its surface, its accessibility to consistent solar illumination, and the scientific and observational data it can make available to Philae’s suite of onboard instruments.
“None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution,” said Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.
Illustration of the Rosetta Missions Philae lander on final approach to a comet surface. The date is now set for landing, November 12. (Photo: ESA)
The mosaic above comprises two images taken by Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) narrow-angle camera on Sept. 14 from a distance of about 30 km (18.6 miles). Image scale is 0.5 m/pixel.
As Comet 67P/CG continues toward perihelion its outgassing and sublimation jetting will undoubtedly increase, and Philae will be getting a front-row seat to the action.
“Site J is just 500-600 meters away from some pits and an area of comet outgassing activity,” said Holger Sierks, principal investigator for Rosetta’s OSIRIS camera from the Max Planck Institute for Solar System Research in Gottingen, Germany. “They will become more active as we get closer to the Sun.”
After completing a series of “Go/No-go” decisions by Rosetta’s flight dynamics team, Philae’s separation from Rosetta will occur on Nov. 12 at 08:35 GMT. It will land about seven hours later at around 15:30 GMT. Because of the distance to the comet and spacecraft — about 509 million km — confirmation of a successful touchdown won’t be received on Earth until 28 minutes and 20 seconds later. (And you thought Curiosity’s “seven minutes of terror” was nerve-wracking!)
On a clear day, astronauts aboard the ISS can see over 1,000 miles from Havana to Washington D.C. Image Credit: Chris Hadfield / NASA
Orbiting 200 miles above the Earth, Retired Astronaut Chris Hadfield could easily photograph the ridges of the Himalayan Mountains, the textures of the Sahara Desert and the shadows cast by the tallest buildings in Manhattan.
Mauritania, also known as the Eye of the Sahara, is a landmark in the vast 3,600,000-square-mile desert. Credit: Chris Hadfield / NASA
“The view of the world when you have it just right there through the visor of your helmet is overpoweringly gorgeous,” said Hadfield, speaking Oct. 14 at the American Museum of Natural History in New York City. “It is phenomenal. The world is pouring by with all its colors and textures so fast.”
Although Hadfield has already shared many of his photos via social media, he unveiled another 150 images in his latest book, “You Are Here: Around The World in 92 Minutes.” The photographs open a rare window onto the Earth, illuminating our planet’s beauty and the consequences of human settlement.
The book is designed to replicate a single 92-minute orbit aboard the International Space Station. “It’s as if you and I are sitting at the window of the space station, and I said, ‘let’s go around the world once. I want to show you the really cool stuff,’ ” said Hadfield.
The astronaut, famed for his zero-gravity rendition of David Bowie’s “Space Oddity,” took approximately 45,000 photos during his 146-day stint on the space station in 2013. That’s roughly 300 photos per day every day. Since NASA does not set aside specific time slots for astronauts to take photos, Hadfield did so while he should have been asleep or serenading millions with his guitar.
The Himalayan mountain range in South Asia. Credit: Chris Hadfield / NASA
Why? Beauty triggers an unexplained emotional reaction, explained Hadfield. It also provides the best means of communication. Although the space station is an incredible scientific laboratory, art is equally important, he added, because it’s a way to reach people who might not otherwise be interested in the scientific nitty-gritty.
Hadfield is often attributed for humanizing space travel in a way that others before him had not. His use of social media, videos designed to quench our curiosity about living in space, and music, demonstrate a sheer passion that has inspired millions.
Manhattan awake at 9:23 a.m. local time, and Manhattan at rest at 3:45 a.m. local time. Credit: Chris Hadfield / NASA
His photos not only share the natural beauty of our home planet, but also many signs of humanity, from bright city lights to the devastations of climate change as lakes dry up and disappear. “There’s so much information in just one glimpse out the window of human decision making and geology,” said Hadfield.
Hadfield’s remote yet vivid photos stand as a reminder of both the magnificence and fragility of life on our planet. “To have the world on one side, like this huge kaleidoscope, and then the bottomlessness of the Universe right there beside you,” said Hadfield, trailing off in awe. “You’re not on the world looking at it. You’re in the Universe with the world.”
Artist's conception of Mars One human settlement. Credit: Mars One/Brian Versteeg
How possible is it to land humans on Mars? And can Mars One, the organization proposing to start with sending four astronauts one way, capable of doing it by 2025 as it promises?
A new study says that the Mars One concept could fail on several points: oxygen levels could skyrocket unsafely. Using the local resources to generate habitability is unproven. The technology is expensive. But the founder of Mars One says the Massachusetts Institute of Technology (MIT) student study is based on the wrong assumptions.
“It’s based on technology available on the ISS [International Space Station],” said Bas Landorp in an interview with Universe Today. “So you end up with a completely different Mars mission than Mars One. So their analysis has nothing to do with our mission.”
The mission has sparked a debate about sending humans on a trip with no promise for a return, but thousands of applicants vied for the chance to do it. After two cuts, the interim shortlist is now at 700 people. Those folks are awaiting interviews (more news is coming shortly, Landorp says) and no date has yet been announced for the next “cut.”
ISRO’s Mars Orbiter Mission captures spectacular portrait of the Red Planet and swirling dust storms with the on-board Mars Color Camera from an altitude of 74500 km on Sept. 28, 2014. Credit: ISRO
A couple of weeks ago, MIT students presented a technical feasibility analysis of Mars One at the International Astronautical Congress in Toronto, Canada. The study is 35 pages long, so we recommend you read it to get the whole picture. The students’ main concerns are that crops (if they are responsible for 100% of the food) would send oxygen levels to unsafe margins, with no way to remove it. There are concerns with how well the in-situ resource utilization (using the resources on Mars to live off of) would perform. And the mission would cost $4.5 billion at a minimum — for the first crew only.
Cost: To get to Mars, the students say it will cost $4.5 billion and take 15 Falcon Heavy launches (a proposed next-generation rocket from SpaceX). Landorp says he can do it for $1.625 billion (since he doesn’t require constant Earth resupply) and as few as 13 launches (assuming $125 million per launch, a figure Landrop says is from SpaceX) by taking advantage of a few quirks of physics. If Mars One chooses a landing site that is four kilometers (2.5 miles) below the average Martian surface height, they will have both a thicker atmosphere and more time to land the payloads than, say, the Curiosity rover that landed about two kilometers (1.24 miles) above the average surface height. Mars One’s numbers show they could carry a payload of 2,500 kilograms (5,512 pounds) per mission, which they say is well within reach of what spacecraft can do today. The 13 launches would be divided into 11 robotic launches to send equipment to the surface, and two for humans (one to head to Earth orbit for assembly, and the other for the colonists to head to the in-orbit spacecraft and fly to Mars. The assembly crew would then fly back to Earth on the launch vehicle.)
Life support: While many of the technologies planned for use in life support are similar to those on the ISS — such as a trace gas system for air revitalization — Landorp says there will be some crucial differences. They are in talks with Paragon Space Systems Corp. (which describes itself as an environmental control firm for extreme environments, and whose customers include NASA and Bigelow.) As for the unsafe oxygen levels, Landorp points out there are plenty of oxygen removal systems available and that are used in hospitals and militaries. All that is needed is more testing in space. Landorp also points out these systems will be tested for two years robotically before humans land. “If that is not successful, then obviously we will not send humans,” he said.
The proposed Falcon Heavy rocket. Credit: SpaceX
In-situ resource utilization: Landorp acknowledges this requires more study, but says the robotic missions will be an important precursor for the human landings. Technologies needing to be developed will include nitrogen extraction from the Martian atmosphere. Oxygen production from water is well-studied in space, but water from the Martian surface (through vaporizing water in the soil) will require more work.
Another concern raised in media from time to time is where the money is coming from to fund Mars One. Landorp says right now funds are flowing from private investors. Mars One representatives are also in serious talks with a United Kingdom-based listed investment fund willing to finance the mission. In the long run, Landorp is confident money will come from broadcast deals similar to what partially fund the Olympics and the Fédération Internationale de Football Association (FIFA) competitions. Associated sponsorships would also help. But these won’t kick in until the colonists launch and land, since that’s when the world’s eyeballs will be on the mission.
Another stream of revenue, which may take five to seven years to kick in, will be intellectual property deals Mars One one representatives are working on closing now with potential suppliers, such as Lockheed Martin and Paragon. These agreements, should they go through as planned, would give Mars One a share of future revenue from any technologies flowing from the IP. “In the short term it’s not that interesting, it takes time to mature, but in the long term that will be interesting,” Landorp said.
An October 2014 gravity map of the Earth's oceans using data from the European Space Agency's CryoSat mission and the CNES-NASA Jason-1 satellite. Findings include "continental connections" between South American and Africa, and evidence of seafloor spreading in the Gulf of Mexico that took place 150 million years ago. The red dots are volcanoes. Credit: Scripps Institution of Oceanography
Volcanoes! Seafloor spreading! Hidden ridges and mountains! These are the wonders being revealed in new maps of Earth’s sea floor. And no, it didn’t require a deep-sea dive to get there. Instead we got this information from a clever use of gravity (combining the data of two satellites making measurements from orbit.)
The data has caught the attention of Google, which plans to use this data for its upcoming ocean maps release. Scientists also say the information will tell us more about the 80% of the ocean floor that is either unexamined or obscured by thick sand.
So here’s where the data came from. The Scripps Institution of Oceanography combined information from two satellites — the European Space Agency’s ongoing CryoSat mission and the now defunct Jason-1 satellite from NASA and the French space agency CNES, which was decommissioned in 2013 after nearly 12 years of operations.
CryoSat is designed to map the thickness of ice using a radar altimeter (which is a clue to the effects of climate change). But this altimeter can be used all over the world, including to look at how high the sea floor is. Jason-1, for its part, was told to look at the Earth’s gravity field in the last year of its mission. And what a world pops out when this data is used.
A 2014 view of the Earth’s sea floor using data from the European Space Agency’s CryoSat mission and the CNES-NASA Jason-1 satellite. Credit: Scripps Institution of Oceanography
“The effect of the slight increase in gravity caused by the mass of rock in an undersea mountain is to attract a mound of water several meters high over the seamount. Deep ocean trenches have the reverse effect,” ESA wrote in a statement. “These features can only be detected by using radar altimetry from space.”
Some of the new findings include finding new bridges between Africa and South America and uncovering seafloor spreading that happened in the Gulf of Mexico 150 million years ago. Results based on the study, led by Scripps’ David Sandwell, recently appeared in the journal Science.
Long-time readers of Universe Today may also recall a gravity map from ESA’s Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), which revealed Earth’s gravity as a lumpy potato shape in 2011.
A collage of moon photos that photographer David Blanchflower took between March and October 2014 from Newcastle upon Tyne, United Kingdom, using a Nikon Coolpix L810 camera. One picture used a telescope (Skywatcher Explorer 200P).
We think of the Moon as a grey and unchanging world, but throw in the effects of Earth’s atmosphere and orbit and you get some really cool effects. It can look yellow or red or almost blue. It changes from a full disc to a crescent and back again. It gets bigger and smaller as the Moon drifts forward and backward in its orbit. Sometimes it’s even eclipsed.
Remarkably, one photographer has captured many of these moods in a single collage. The picture above from David Blanchflower was recently posted to the Universe Today Flickr pool, showing images between March and October 2014.
“All from Newcastle upon Tyne with a Nikon Coolpix L810 Camera,” Blanchflower wrote. “One of the pictures was taken with the aid of a telescope (Sky-Watcher Explorer 200P). They show a variety of colours and phases.”
We’d love to see your shots of the moon as well, so please feel free to contribute to the Flickr pool. Posting a picture means we could use it in a future story.
Oh, to be a stranded astronaut on the surface of the planet Mars this week. There’s a great scene from Andy Weir’s recent novel The Martian where chief protagonist Mark Watney uses the swift moving moons of Phobos and Deimos to roughly gauge his direction while travelling across the expansive Martian desert.
This week, the skies over Mars will also be graced by an unforgettable and spectacular sight: the extremely close passage of Comet C/2013 A1 Siding Spring. The first comet discovered in 2013, A1 Siding Spring was spotted by veteran comet hunter Robert McNaught from the Siding Spring Observatory in Australia. Dozens of comets are discovered in any given year, but this one soon gained the attention of astronomers when it was found that the comet could possibly hit Mars in October 2014.
And although further observations refined A1 Siding Spring’s orbit and ruled out such an impact, the particulars of the close passage of the comet past Mars are still stunning: A1 Siding Spring will pass within 87,000 miles (139,500 kilometres) from the center of Mars on Sunday, October 19th at 18:27 Universal Time (UT) or 2:27 PM EDT.
And although we’ve yet to set “boots” on Mars, a fleet of spacecraft arrayed throughout the inner solar system are set to study the comet from both near and far. NASA has taken measures to assure that spacecraft in orbit are afforded maximum protection from incoming cometary debris, and the exciting possibility exists that we’ll be able to study first-hand the interaction of the comet’s tail with the Martian atmosphere.
Mars-based spacecraft set to observe Comet A1 Siding Spring: a scorecard. Credit: NASA.
Universe Today has written extensively on the scientific efforts to study the event, how to observe the comet from Earth, and the unprecedented amateur and professional campaign in progress to witness the close pass.
What we’d like to do now is imagine the unparalleled view under alien skies as the comet slides gracefully overhead.
The nucleus of A1 Siding Spring is thought to be 700 metres across, and the coma extends 19,300 km in diameter. The comet’s closest passage is just under six times the distance of Mars’ outer moon Deimos, and at closest approach, the coma will appear almost 8 degrees in size to any would-be Martian — that’s 16 times the diameter of a Full Moon as seen from the Earth — and will be crossing the skies at a staggering 1.5 degrees a minute. You would be able to easily see the motion of the comet as it moves across the Martian sky with the unaided (well, space suit helmet protected) eye after just a few dozen seconds worth of watching! The comet’s magnitude may reach -5 as seen from Mars, though that would also be extended over its huge expanded surface area.
The enormous tail of the comet would also span the sky, and NASA has already released several mind blowing simulations to this effect. We’ve also constructed some brief simulations using Starry Night that show the view of the encounter from Earth, Phobos, and the perspective from the comet itself:
There’s also been some discussion as of late that A1 Siding Spring has slowed down in terms of its predicted brightening, though this is not unusual or unexpected.
From Acidalia Planitia (the setting for The Martian) located in the mid-northern latitudes on the surface of Mars, the comet would be a fine morning object, sitting 48 degrees above the northeastern horizon at dawn at closest passage for one morning only, and perhaps staying visible even after sunrise. Earth would be in the picture too, shining at magnitude -2.5 in the Martian dawn.
Dawn on October 19th, 2014, as seen from Mars. Created using Starry Night.
And the view from the comet? Now that would be a truly spectacular ride, as Mars swells to 3 degrees in diameter as it approaches and recedes. The comet itself is on a million year plus orbit, never to again visit the realm of the inner solar system in our lifetimes.
Such a view has never been seen in recorded history from the Earth. The closest confirmed passage of a large comet near our planet was Comet D/1770 L1 Lexell, which passed over 15 times more distant than A1 Siding Spring from Mars, at 2.2 million km from Earth on July 1st, 1770. Note that an even closer cometary passage in 1491 remains unverified. In more recent times, Comet Hyakutake passed 15.8 million km from Earth on March 25th, 1996, with a tail that spanned half the sky as seen from a dark sky site, and long-time comet observers might also remember the 1983 passage of Comet IRAS-Araki-Alcock, which passed just 4.7 million kilometres from the Earth.
A1 Siding Spring imaged from Earth on October 11th, 2014. Credit: Efrain Morales Rivera.
And then there was the historic impact on Comet Shoemaker-Levy 9 into Jupiter in 1994, reminding us that cosmic catastrophes can and do indeed occur… the upper size limit estimate for the nucleus of A1 Siding Spring compares to 70% the size of Fragment G, and an impact on Earth or Mars of such a dirty snowball would be a very bad day, for rovers or the humans. An extinction level event such as the Chicxulub impactor, however, was estimated to be much larger, at about 10 km in size.
A1 Siding Springs as imaged on September 3rd, 2014. Credit: Roger Hutchinson.
Thankfully, we’ve merely got a front row seat to the show this weekend, and our planet is not the main event. From Earth, Comet A1 Siding Spring will be a binocular object, shining at magnitude +9 as it passes 3’ from +0.9 magnitude Mars. Both will be visible briefly in dusk skies, and the Virtual Telescope Project also plans to broadcast the event live starting at 16:45 UT on October 19th.
Don’t miss the historic passage of Comet A1 Siding Spring past Mars… by this time next week, we fully expect more images of the comet — both amateur and professional — to grace the cyber-pages of Universe Today!
Imaging A1 Siding Spring and/or Mars? Send those astro-pics into Universe Today at our Flickr forum.
Are you scared of the dark, personal failure, or just feeling a tad nihilistic? Maybe you’re worried about asteroids, solar flares, or the heat death of the Universe… or perhaps you’ve just misplaced your favorite winter accessory and it’s driving you… er, nuts. If any of these are applicable (or even if none is) be sure to watch the ridiculously award-winning video above by animator Eoin Duffy. (And if you’re wondering why I’m sharing this on Universe Today, well… you’ll see.)
