Saturn is divided by its rings and the moons Tethys and Epimetheus. Credit: NASA/JPL/Space Science Institute
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Two moons and Saturn’s rings create a lopsided “divided by” symbol on the giant planet in one of the latest images released by the Cassini science team. The rings also cast shadows and darken the southern hemisphere of the planet. The moon Tethys (1,062 kilometers, or 660 miles across) sits above the rings, while the smaller moon Epimetheus (113 kilometers, or 70 miles across) hovers below. This image was taken by Cassini’s narrow-angle camera on March 8, 2011. See below for a few more recent looks at Saturn.
The moon Prometheus sits amid Saturn's rings. Credit: NASA/JPL/Space Science InstituteA dark Saturn with rings and shadows. Credit: NASA/JPL/Space Science Institute
Check out more images on the Cassini website. There are some brand new images in the “raw image” section, including some great looks at Titan. And look for more great images of Titan soon, as Cassini’s next close flyby of Saturn’s largest moon will be on May 8.
Although we couldn’t remind you just before the date of the Lyrid meteor shower peak, there’s no reason to believe the show is over just yet! If you’re an early riser, this just might be your chance to catch a lingering Lyrid…
Every year the Earth encounters the dusty remnants of the tail of Comet Thatcher (C/1861 G1). It doesn’t occur on a very specific date, but we do know it happens in late April. While the peak time is dawn on April 23, it’s not uncommon to see between 5-20 meteors per hour through the 26th.
Why such a widely varied date and diversified fall rate? The answer is… thanks to Jupiter’s massive gravity, we never know exactly when we might encounter a “clump” of comet debris. The majority of the time, the spawn of Comet Thatcher is no bigger than a grain of sand, traveling through our atmosphere at 49 km/s (110,000 mph). Incredibly enough, these fast moving particles can light up as brightly as 2nd magnitude – easily seen from moderately light polluted skies. Some have even been known to appear as fireballs and leave smoke-like trails that linger in the sky for several minutes!
For the past 2600 years, mankind has been observing the Lyrids – and you can, too. Since their radiant is near the bright star, Vega, your best time to observe is in the hours just before dawn. For many observers, the constellation of Lyra will be high to the east around 4:30 a.m. local time and nearly overhead just before dawn. Even southern hemisphere observers with an unobstructed northern horizon can enjoy the show, too. While there will be some Moon to contend with, placing it behind an obstruction like the corner of a building or a tree will help reduce the glare.
Clouded out or decided to sleep until it was light? Don’t forget your lessons on how to “listen” with your radio! According to NASA, “This year many amateur radio operators tuned into the Lyrids using a technique called radio forward scattering. When fast-moving meteoroids strike Earth’s atmosphere they heat and ionize the air in their path. The luminous ionized trails are not only visually striking — they also reflect radio waves. During a major meteor shower, radio signals from TV stations, RADAR facilities, and AM/FM transmitters are constantly bouncing off short lived meteor trails. For those who know how to listen, it’s easy to hear the echoes.” Don’t remember how to listen? Then take the radio meteor listening tutorial courtesy of the North American Meteor Network.
Will you catch a lingering Lyrid? You never know until you try…
Many thanks to John Chumack of Galactic Images and to NASA for the illustrations.
Over the past year, the Sun has gone from one of quietest periods in decades to the ramping up of activity marking the beginning of Solar Cycle 24. And with impeccable timing, the Solar Dynamics Observatory has been there, in orbit, capturing every moment with a level of detail never-before possible. The mission has returned unprecedented images of solar flares, eruptions of prominences, and the early stages of coronal mass ejections (CMEs). It was on April 21st, 2010 that the SDO scientists were able to reveal the first images from their fledgling satellite, and now, one year on, who has not loved the intricate details of old Sol that we’ve been able to see in the imagery and video SDO has provided!
This video shows some of the most beautiful and compelling solar events seen by SDO so far, and at the SDO website, you can vote for your favorite. The contest runs through Thursday May 5, 2011. Check back on May 6 to see which video the public selected as their all-time favorite SDO video from the past year.
An artist’s impression of WASP 12-b being slowly consumed as a result of its ridiculously tight orbit around its star. More recent observations suggests the exoplanet has a magnetosphere which may be partially protecting it from stellar wind erosion. Credit: NASA.
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New observations of one of the biggest and hottest known exoplanets in the galaxy, WASP 12b, suggest that it is generating a powerful magnetic field sufficient to divert much of its star’s stellar wind into a bow shock wave.
Like exoplanets themselves, the discovery of an exo-magnetosphere isn’t that much of a surprise – indeed it would be a surprise if Jovian-type gas giants didn’t have magnetic fields, since the gas giants in our own backyard have quite powerful ones. But, assuming the data for this finding remains valid on further scrutiny, it is a first – even if it is just a confirming-what-everyone-had-suspected-all-along first.
WASP-12 is a Sun-like G type yellow star about 870 light years away from Earth. The exoplanet WASP-12b orbits it at a distance of only 3.4 million km out, with an orbital period of only 26 hours. Compare this to Mercury’s orbital period of 88 days at a 46 million kilometer distance from the Sun at orbital perihelion.
So habitable zone, this ain’t – but a giant among gas giants ploughing through a dense stellar wind of charged particles sounds like an ideal set of circumstances to look for an exo-magnetosphere.
The bow shock was detected by an initial dip of the star’s ultraviolet light output ahead of the more comprehensive dip which was produced by the transiting planet itself. Given the rapid orbital speed of the planet, some bow wave effect might be expected regardless whether or not the planet generates a strong magnetic field. But apparently, the data from WASP 12-b best fits a model where the bow shock is produced by a magnetic, rather than just a dynamic physical, effect.
The finding is based on data from the SuperWASP (Wide Angle Search for Planets) project as well as Hubble Space Telescope data. Team leader Dr. Aline Vidotto of the University of St. Andrews said of the new finding. “The location of this bow shock provides us with an exciting new tool to measure the strength of planetary magnetic fields. This is something that presently cannot be done in any other way.”
Although WASP 12b’s magnetic field may be prolonging its life somewhat, by offering some protection from its star’s stellar wind – which might otherwise being blowing away its outer layers – WASP 12-b is still doomed due to the gravitational effects of the close-by WASP 12 star which has already been observed to be drawing material from the planet. Current estimates are that WASP 12-b will be completely consumed in about 10 million years.
WASP 12-b is not only one of the hottest hot Jupiters we've found, but also one of the biggest (although this may be largely a result of expansion due to heating).
There is at least one puzzle here, not really testable from such a distance. Presuming that a planet so close to its star is probably tidally-locked, it would not be spinning on its axis – which is generally thought to be a key feature of planets generating strong magnetic fields – at least the ones in our Solar System. This may need something like an OverwhelminglySuperWASP to investigate further.
Can chocolate cream eggs help explain the mysteries of the Universe? As part of the University of Nottingham’s Sixty Symbols science video series, the Cadbury creme egg has been featured this week, with several eggcellent videos just in time for Easter. This one discusses the cosmological constant, and the possibility of how we might be surrounded by tiny eggs from another dimension. Surprisingly, scientists can explain and demonstrate the some fundamental scientific laws that govern the universe with yummy cream filled chocolate eggs. See more egg-themed discussions at Sixty Symbols.
A disk of debris around a star is a likely indicator of planets. A disk of debris with a wildly atypical chemistry could mean aliens.
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Recently, some researchers speculated on what types of observational data from distant planetary systems might indicate the presence of an alien civilization, determined that asteroid mining was likely to be worth looking for – but ended up concluding that most of the effects of such activity would be difficult to distinguish from natural phenomena.
And in any case, aren’t we just anthropomorphizing by assuming that intelligent alien activity will be anything like human activity?
Currently – apart from a radio, or other wavelength, transmission carrying artificial and presumably intelligent content – it’s thought that indicators of the presence of an alien civilization might include:
• Atmospheric pollutants, like chlorofluorocarbons – which, unlike methane or molecular oxygen, are clearly manufactured rather than just biogenically produced
• Propulsion signatures – remember how the Vulcans detected humanity in First Contact (or at least they decided we were worth visiting after all, despite all the I Love Lucy re-runs)
• Stellar engineering – where a star’s lifetime is artificially extended to maintain the habitable zone of its planetary system
• Dyson spheres – or at least their more plausible off-shoots, such as Dyson swarms.
And perhaps add to this list – asteroid mining, which would potentially create a lot of dust and debris around a star on a scale that might be detectable from Earth.
There is a lot of current interest in debris disks around other stars, which are detectable when they are heated up by the star they surround and then radiate that heat in the infra-red and sub-millimeter wavelengths. For mainstream science, debris disk observations may offer another way to detect exoplanets, which might produce clumping patterns in the dust through gravitational resonance. Indeed it may turn out that the presence of a debris disk strongly correlates with the existence of rocky terrestrial planets in that system.
But now going off the mainstream… presuming that we can eventually build up a representative database of debris disk characteristics, including their density, granularity and chemistry derived from photometric and spectroscopic analysis, it might become possible to identify anomalous debris disks that could indicate alien mining activities.
Some recent astronomy pareidolia. Not an alien mining operation on Mercury, but a chunk of solidified ejecta commonly found in the center of many impact craters. Credit: NASA.
For example, we might see a significant deficiency in a characteristic element (say, iron or platinum) because the aliens had extracted these elements – or we might see an unusually fine granularity in the disk because the aliens had ground everything down to fine particles before extracting what they wanted.
But surely it’s equally plausible to propose that if the aliens are technologically advanced enough to undertake asteroid mining, they would also do it with efficient techniques that would not leave any debris behind.
The gravity of Earth makes it easy enough to just blow up big chunks of rock to get at what you want since all the debris just falls back to the ground and you can sort through it later for secondary extraction.
Following this approach with an asteroid would produce a floating debris field that might represent a risk to spacecraft, as well as leaving you without any secondary extraction opportunities. Better to mine under a protective canopy or just send in some self-replicating nanobots, which can separate out an enriched chunk of the desired material and leave the remainder intact.
If you’re going to play the alien card, you might as well go all in.
Artist's illustration of Pluto's surface. Credit: NASA
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Ah, Pluto. Seems every time we think we’ve got it figured out, it has a new surprise to throw at us.
First spotted in 1930 by a young Clyde Tombaugh, for 76 years it enjoyed a comfortable position as the solar system’s most distant planet. Then a controversial decision in 2006 by the International Astronomical Union, spurred by suggestions from astronomer (and self-confessed “planet-killer”) Mike Brown*, relegated Pluto to a new class of worlds called “dwarf planets”. Not quite planets and not quite asteroids, dwarf planets cannot entirely clear their orbital path with their own gravitational force and thus miss out on full planetary status. Besides immediately making a lot of science textbooks obsolete and rendering the handy mnemonic “My Very Eager Mother Just Served Us Nine Pies” irrelevant (or at least confusing), the decision angered many people around the world, both in and out of the scientific community. Pluto is a planet, they said, it always has been and always will be! Save Pluto! the schoolkids wrote in crayon to planetarium directors. The world all of a sudden realized how much people liked having Pluto as the “last” planet, and didn’t want to see it demoted by decision, especially a highly contested one.
Yet as it turns out, Pluto really may not be a planet after all.
It may be a comet.
But…that’s getting ahead of ourselves. First things first.
Discovery data showing carbon monoxide spectrum. Credit: J.S. Greaves / Joint Astronomy Centre.
Recent discoveries by a UK team of astronomers points to the presence of carbon monoxide in Pluto’s atmosphere. Yes, Pluto has an atmosphere; astronomers have known about it since 1988. At first assumed to be about 100km thick, it was later estimated to extend out about 1500km and be composed of methane gas and nitrogen. This gas would expand from the planet’s – er, dwarf planet’s – surface as it came closer to the Sun during the course of its eccentric 248-year orbit and then freeze back onto the surface as it moved further away. The new findings from the University of St Andrews team, made by observations with the James Clerk Maxwell telescope in Hawaii, identify an even thicker atmosphere containing carbon monoxide that extends over 3000 km, reaching nearly halfway to Pluto’s largest moon, Charon.
It’s possible that this carbon monoxide atmosphere may have expanded outwards from Pluto, especially in the years since 1989 when it made the closest approach to the Sun in its orbit. Surface heating (and the term “heating” is used scientifically here…remember, at around -240ºC (-400ºF) Pluto would seem anything but balmy to us!) by the Sun’s radiation would have warmed the surface and expelled these gases outwards. This also coincides with observations made by the Hubble Space Telescope over the course of four years, which revealed varying patterns of dark and light areas on Pluto’s surface – possibly caused by the thawing of frozen areas that shift and reveal lighter surface material below.
“Seeing such an example of extra-terrestrial climate-change is fascinating. This cold simple atmosphere that is strongly driven by the heat from the Sun could give us important clues to how some of the basic physics works, and act as a contrasting test-bed to help us better understand the Earth’s atmosphere.”
– Dr. Jane Greaves, Team Leader
In fact, carbon monoxide may be the key to why Pluto even still has an atmosphere. Unlike methane, which is a greenhouse gas, carbon monoxide acts as a coolant; it may be keeping Pluto’s fragile atmosphere from heating up too much and escaping into space entirely! Over the decades and centuries that it takes for Pluto to complete a single year, the balance between these two gases must be extremely precise.
So here we have Pluto exhibiting an expanding atmosphere of thawing expelled gas as it gets closer to the Sun in an elliptical, eccentric orbit. (Sound familiar?) And now there’s another unusual, un-planet-like feature that’s being put on the table: Pluto may have a tail.
Actually this is an elaboration of the research results coming from the same team at the University of St Andrews. The additional element here is a tiny redshift detected in the carbon monoxide signature, indicating that it is moving away from us in an unusual way. It’s possible that this could be caused by the top layers of Pluto’s atmosphere – where the carbon monoxide resides – being blown back by the solar wind into, literally, a tail.
That sounds an awful lot, to this particular astronomy reporter anyway, like a comet.
Just saying.
Anyway, regardless of what Pluto is or isn’t, will be called or used to be called, there’s no denying that it is a fascinating little world that deserves our attention. (And it will be getting plenty of that come July 2015 when the New Horizons spacecraft swings by for a visit!) I’m sure there’s no one here who would argue that fact.
New Horizons’ upcoming visit will surely answer many questions about Pluto – whatever it is – and most likely raise even more.
Artist's impression of Pluto's huge atmosphere of carbon monoxide.Credit:P.A.S. Cruickshank.
The new discovery was presented by team leader Dr. Jane Greaves on Wednesday, April 20 at the National Astronomy Meeting in Wales.
Article reference: arxiv.org/abs/1104.3014: Discovery Of Carbon Monoxide In The Upper Atmosphere Of Pluto
*No disrespect to Mr. Brown intended…he was just performing science as he saw fit!
As you probably noticed, Universe Today was unavailable for the last couple of days. The site is hosted with Amazon.com’s EC2 service, which has been very stable up until now. But the entire East Coast data center failed early Thursday morning, taking out hundreds of thousands of websites (including Universe Today). This has been a PR disaster for Amazon, so I’m assuming they’re going to go out of their way to make sure it never, ever happens again. Obviously, I’m also going to be making better contingency plans as well.
Sorry for the disruption, let’s hope everything’s stable from this point on.
President Obama plans to attend the last launch of Endeavour on April 29, 2011 at the Kennedy Space Center. President Obama last visited the Kennedy Space Center in Florida on April 15, 2010 and outlined the new course his administration is charting for NASA and the future of U.S. human spaceflight. Credit: NASA/Kim Shiflett
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President Barack Obama and the entire First Family apparently plan to attend the final launch of Space Shuttle Endeavour, according to government officials and multiple news outlets. Endeavour is slated to blast off on the STS-134 mission next Friday, April 29 from the Kennedy Space Center (KSC) in Florida at 3:47 p.m. EDT.
There has already been intense drama surrounding the STS-134 mission because it is being commanded by Mark Kelly. Kelly is the husband of U.S. Congresswoman Gabrielle Giffords of Arizona who was critically wounded by gunshots to her head at point blank range during an assassination attempt while attending a meet and greet with her constituents on Jan. 8, 2011. Six people – including a nine year old girl and a federal judge – were killed and a dozen more were wounded that awful day.
Space Shuttle Endeavour awaits her final launch on April 29, 2011 from Pad 39A at the Kennedy Space Center, FL Credit: Ken Kremer
The Presidents appearance at the STS-134 launch will almost certainly lead to skyrocketing interest, but has not yet been officially announced by NASA and the White House. The event is not yet listed on the presidents official schedule.
However, a tweet by the staff of Congresswoman Giffords on her official website states Obama will attend; “We are very happy that Pres. Obama is coming to Mark’s launch! This historic mission will be #Endeavours final flight.”
NASA spokesman Allard Beutel told me today, “I cannot confirm whether the president will be coming to launch next week. If he’s coming, which I can’t confirm, we are a White House agency.”
“We always welcome a visit from the President,” Beutel said.
Security is always tight at KSC during a shuttle launch. A visit by President Obama will certainly lead to even tighter security controls and even more massive traffic jams.
Giant crowds were already expected for this historic final spaceflight of Space Shuttle Endeavour, NASA’s youngest Orbiter, on her 25th mission to space.
Endeavour is carrying the $2 Billion Alpha Magnetic Spectrometer (AMS) ) on a 14-day flight to the International Space Station, a premier science instrument that will collect cosmic rays, search for dark energy, dark matter and anti matter and seeks to determine the origin of the Universe. See my photo below of the AMS from inside the Space Station Processing Facility (SSPF) at KSC with the principal investigator, Nobel Prize winner Prof. Sam Ting of MIT.
President Obama last visited KSC on April 15, 2010 and gave a major policy speech outlining his radical new human spaceflight goals for NASA. Obama decided to cancel NASA’s Project Constellation ‘Return to the Moon’ Program and the Ares 1 and Ares 5 rockets. He directed NASA to plan a mission for astronauts to visit an Asteroid by 2025 and one of the moons of Mars in the 2030’s. Obama also decided to revive the Orion crew module built by Lockheed Martin, which is now envisaged for missions beyond low earth orbit (LEO), and invest in development of new commercial space taxis such as the Dragon spacecraft by SpaceX for transporting astronaut crews to the ISS.
Spokesman Beutel said that during the April 2010 visit, “The President met with space workers.” He could not comment on details of the president’s plans for the STS-134 visit and said information would have to come from the White House.
The last time a sitting president watched a live human space launch was in 1998 when then President Bill Clinton attended the blastoff of the return to space of Astronaut and Senator John Glenn. Glenn was the first American to orbit the Earth back in 1962. Glenn’s first flight took place a little over a year after the historic first human spaceflight by Soviet Cosmonaut Yuri Gagarin on April 12, 1961- which occurred exactly 50 years ago last week.
Congresswoman Giffords is recovering from her wounds and Shuttle Commander Kelly has said that she would like to attend the STS-134 launch. But no official announcement about her attendance has been made by NASA and depends on many factors including decisions by the doctors treating her in a Houston area hospital.
The Alpha Magnetic Spectrometer (AMS) and Nobel Prize Winner and Principal Investigator Sam Ting of MIT - inside the Space Station Processing Facility at KSC. The STS-134 mission of shuttle Endeavour will deliver the AMS to the ISS. The AMS purpose is to try and determine the origin of the Universe. . Credit: Ken KremerClose up of Endeavour crew cabin, ET, SRB and astronaut walkway to the White Room. Credit: Ken Kremer
The largest solar flare recorded in nearly five years was triggered by interactions between five rotating sunspots, say researchers who studied observations of the flaring region of the Sun taken by the Solar Dynamics Observatory over a period of five days. The flare occurred at 1.44am on February 15,2011, when the Sun released the largest recorded solar flare since December 2006 and the first flare of the current solar cycle to be classified as the most powerful “X-class”. Continue reading “Interacting Sunspots Spawn Gigantic Solar Flare”
