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.)
Artist's impression of the 100-kg Philae lander (screenshot) Credit: ESA/DLR
In less than a month, on November 12, 2014, the 100-kg Philae lander will separate from ESA’s Rosetta spacecraft and descend several kilometers down to the dark, dusty and frozen surface of Comet 67P/Churyumov-Gerasimenko, its three spindly legs and rocket-powered harpoon all that will keep it from crashing or bouncing hopelessly back out into space. It will be the culmination of a decade-long voyage across the inner Solar System, a testament to human ingenuity and inventiveness and a shining example of the incredible things we can achieve through collaboration. But first, Philae has to get there… it has to touch down safely and successfully become, as designed, the first human-made object to soft-land on the nucleus of a comet. How will the little spacecraft pull off such a daring maneuver around a tumbling chunk of icy rubble traveling over 18 km/s nearly 509 million km away? The German Aerospace Center (DLR) has released a “trailer” for the event, worthy of the best sci-fi film. Check it out below.
Want to see more? Of course you do. Keep an eye out for the 11-minute short film “Landing on a Comet – The Rosetta Mission” to be released soon on YouTube here, and follow the latest news from the Rosetta mission here (and here on Universe Today, too!)
“The reason we’re at this comet is for science, no other reason. We’re doing this to get the best science. To characterize this comet has never been done before.”
Original Material: DLR (CC-BY 3.0)
Footage: ESA
Credit 67P image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Music: Omega by TimMcMorris
And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.
The Rosetta spacecraft takes a selfie Oct. 7 with its target, 67P/Churyumov–Gerasimenko, from an altitude of about 9.9 miles (16 kilometers). Credit: ESA/Rosetta/Philae/CIVA
So this spacecraft — taking this picture — is going to land on the surface of THAT comet. Doesn’t this give you a pit in your stomach? This is a selfie taken from the Philae spacecraft that, riding piggyback, captured the side of the Rosetta spacecraft orbiting Comet 67P/Churyumov-Gerasimenko.
The image is so close-up — just 9.9 miles (16 kilometers) from 67P’s surface — that mission planners can even spot Landing Site J on the comet’s smaller lobe.
“Two images, one with a short exposure time, one with a longer one, were combined to capture the whole dynamic range of the scene, from the bright parts of the solar arrays to the dark comet and the dark insulation cladding the Rosetta spacecraft,” the European Space Agency stated.
It’s quite the zoom-in after the last selfie that Philae produced for the public in September, which was taken from 31 miles (50 kilometers) away. The spacecraft is expected to make the first touchdown ever on a comet next month. Rosetta, meanwhile, will keep following 67P as it gets closest to the sun in 2015, between the orbits of Earth and Mars.
Tomorrow (Oct. 15), mission managers will announce if Site J is go or no go for a landing. More information is coming from Rosetta’s examination of the site from its new, lower altitude of 6.2 miles (10 kilometers).
Artist's conception of CubeSats near Europa (left) and Jupiter. Credit: NASA/JPL
When you’ve got a $2 billion mission concept to head to Europa, it’s likely a good idea to pack as much science on this mission as possible. That’s the thinking that NASA had as it invited 10 universities to send their ideas for CubeSats — tiny satellites — that would accompany the Europa Clipper mission to the Jupiter system.
Europa Clipper is only on the drawing board right now and not fully funded, and should not be confused with the lower-cost $1 billion Europa mission that NASA proposed earlier this year (also not fully funded). But however NASA gets there, the agency is hoping to learn if the moon could be a good spot for life.
Each university is being awarded up to $25,000 to develop their ideas further, and they will have until next summer to work on them. Investigations include searching the surface for future landing sites, or examining Europan properties such as gravity, its atmosphere, magnetic fields or radiation.
Two reddish spots (Thera and Thrace) stick out on this image of Europa taken by the Galileo orbit in the 1990s. NASA says they display “enigmatic terrain.” Credit: NASA/JPL/University of Arizona
“Using CubeSats for planetary exploration is just now becoming possible, so we want to explore how a future mission to Europa might take advantage of them,” said Barry Goldstein, pre-project manager for the Europa Clipper mission concept, in a press release.
If Europa Clipper flies, it would do at least 45 flybys at altitudes between 16 miles and 1,700 miles (25 kilometers and 2,700 kilometers.) Part of its expense comes from the long distance, and also from all the radiation shielding the spacecraft would need as it orbits immense Jupiter.
Science instruments are still being figured out, but some ideas include radar (to look under Europa’s crust), an infrared spectrometer (to see what is on the ice), a camera to image the surface and a spectrometer to look at the moon’s thin atmosphere.
While there are no Europa missions officially booked now, NASA does have an active spacecraft called Juno that will arrive at Jupiter in July 2016.
Artist's conception of one of the Solar TErrestrial RElations Observatory (STEREO) spacecraft. Credit: NASA
A NASA spacecraft has been out of radio contact for about two weeks, but the agency is still holding out hopes for a rescue. One of the STEREO (Solar TErrestrial RElations Observatory) spacecraft stopped phoning home to Earth on Oct. 1 “immediately after a planned reset of the spacecraft”, NASA said in an update last week.
If the STEREO-Behind spacecraft can’t be recovered, this could cause a data gap in the mission next year — which is unique because it looks at the far side of the Sun. On the website, NASA didn’t say how badly solar weather forecasts are affected, but in other materials they have said both STEREO spacecraft are a crucial part of this work.
STEREO’s pair of satellites (STEREO-Ahead and STEREO-Behind) aim to better map Sun eruptions (known as “coronal mass ejections”) whose charged particles can disrupt satellite communications during solar storms. The mission has been ongoing since 2006 and they’ve viewed the far side of the Sun since 2011. What caused one of them to stop talking to us is unknown, but NASA said recovery attempts are ongoing.
The satellites’ orbits around the Sun are similar to the Earth’s, but one circles a bit faster and the other a bit slower. Next year, geometry (a solar conjunction) means the Sun will block our view of one of the spacecraft at a time. As NASA explained in a July update, “radio receivers on Earth will not be able to distinguish STEREO’s signal from the sun’s radiation.”
This is affecting the mission in two ways. First, there is a period where the antennas on the spacecraft must be repositioned to avoid getting cooked by the Sun. Some data will flow, but it will be in lower resolution. STEREO-Ahead entered this period on Aug. 20, and STEREO-Behind was supposed to send high-resolution data until Dec. 1.
Then there’s a time when each spacecraft will be completely blocked by the Sun. STEREO-Behind was supposed to enter this period from Jan. 22 to March 23, 2015, with its twin still collecting data at this time. But then will come a period where STEREO-Ahead will be out of contact: March 24 to July 7, 2015. If STEREO-Behind can’t fill in for STEREO-Ahead at this time as planned, a data gap could loom.
Lower-resolution data is then expected from STEREO until 2016, when the geometry means the spacecraft can safely reposition their antennas. While these aren’t the only sun-gazing spacecraft — real-time data is still flowing from the Solar Dynamics Observatory (SDO) and the Solar and Heliospheric Observatory (SOHO) — NASA has said that the lower data rate and losing contact with one STEREO spacecraft next year will be difficult for solar forecasting.
“Lack of STEREO observations used in NASA research models will severely limit the forecasting of solar storms throughout the solar system,” the agency said in a July Q&A about the 2015 data losses.
On October 31st 2005, trick-or-treaters across the central U.S. eastern seaboard were treated to a brilliant fireball, a celestial spectacle that frequently graces October skies.
Mid- to late October is fireball season, a time when several key meteor showers experience a broad peak. We’re already seeing an uptick in fireball activity as monitored by numerous all-sky cameras this month, including NASA’s system positioned across the United States. Three lesser known but fascinating showers are the chief culprits.
A Bay area fireball captured in 2012. Credit: NASA/Robert P. Moreno Jr.
The main meteor shower on tap for the month of October is the Orionids. This shower radiates from the Club of the constellation Orion, and is the product of that most famous comet of them all, 1P Halley. Halley’s Comet is actually the source of two annual meteor showers, the October Orionids and the May Eta Aquarids. We’re seeing the inward stream of Halley debris in October, and Orionid velocities average a swift 66 kilometres a second. The radiant rides highest for northern hemisphere observers at 4 AM local, and 2014 sees an estimated zenithal hourly rate (ZHR) of 20 predicted to arrive on the mornings of October 21st through the 22nd. The Orionids experience a broad peak spanning October 21st through November 7th, and 2014 sees the peak arrive just two days prior to the Moon reaching New phase. The Orionids have exhibited an uptick in activity as high as 50-75 per hour from 2005-2007, and it’s been suggested that a 12 year peak cycle may govern the Orionids, as the path of meteoroid debris stream is modified by the gravitational influence of the giant planet Jupiter.
A recent early Orionid meteor. Credit: Sharin Ahmad @Shahgazer.
Two other nearby radiants in the sky also produce an exceptionally large number of fireballs in late October: the Southern Taurids and Northern Taurids. These are complex streams laid down by the periodic comet 2P Encke, which possesses the shortest orbital period of any comet known at 3.3 years. Though the ZHR for both is only slightly above the background sporadic rate for northern hemisphere Fall at about five per hour, the Taurids also produce a high ratio of fireballs. The southern Taurids peak in early October and are already active, and the Northern Taurids peak in late October through early November, earning them the nickname the “Fireballs of Halloween”. Unlike many meteor showers, the Northern Taurids are approaching the Earth from behind in our orbit and have a slow relative atmospheric entry velocity of 28 kilometres per second. This makes for long, stately meteor trains often visible in the evening hours before local midnight.
The Taurids also seem to exhibit a seven year periodicity that begs for further study. 2008 was a fine year for Taurid fireballs… could 2015 be next?
Of course, the exact definition of a “fireball” meteor varies by source, though we prefer the definition of a fireball as a meteor brighter than magnitude -3. A fireball reaching -14 (a Full Moon equals magnitude -13, about 2.5 times fainter) is often termed a bolide.
Comet 1P/Halley’s orbital path through the inner solar system. (Credit: NASA/JPL).
Observing meteor showers such as the Orionids is as simple as sitting back and patiently watching the skies. Our own personal rule while starting a meteor vigil is to scan the skies for 10 minutes; one or more meteor sightings is a good sign to keep on watching, while no meteors means it’s time to pack it in and instead maybe write about astronomy. Dark, moonless skies are key, and you can report how many meteors you see to the International Meteor Organization. Be sure to keep a pair of binoculars handy to examine any lingering smoke trails post-fireball passage.
The positions of the radiants of the Orionids and the Taurids, with peak dates. Credit: Stellarium.
Of course, seeing a Taurid fireball is largely a matter of luck and looking at the right place in the sky at the right time. All-sky cameras work great in this regard, and many amateurs now use tripod mounted DLSRs set to take wide-field exposures of the sky automatically throughout the night. Just watch out for dew! Nearly every meteor we’ve caught on camera turned up only in post review, a testament to how much of the sky a lone pair of eyes still misses.
Spot a fireball? The American Meteor Society maintains a great online database of recent sightings and reports. Keep in mind, lots of “meteor-wrongs” inevitably crop up on Facebook and Twitter during any event, posted by folks eager for likes and retweets. Faves of such spoofers are: the Peekskill meteor train, the reentry of Hyabusa, Mir, and scenes (!) from the movie Armageddon. We’ve seen ‘em all passed off as legit, though you’re more than welcome to try and be original… a majority of initial meteor images almost always come from dash cams (remember Chelyabinsk?) and security cameras.
Finally, in addition to fireballs, there’s another astronomical tie-in for Halloween, as it’s one of four cross-quarter tie-in days approximately mid-way between a solstice and an equinox. The other three are: Lammas Day (August 1st), Groundhog’s Day (February 2nd) and May Day (May 1st). We just think that it’s great — if a bit paradoxical — to see modern day suburbanites dress up as ghouls and goblins as they reenact archaic rites and holidays…
Don’t forget to keep an eye out for the fireballs of October this Halloween!
