Here’s this week’s image for the WITU Challenge, to test your visual knowledge of the cosmos. You know what to do: take a look at this image and see if you can determine where in the universe this image is from; give yourself extra points if you can name the spacecraft responsible for the image. We’ll provide the image today, but won’t reveal the answer until tomorrow. This gives you a chance to mull over the image and provide your answer/guess in the comment section. Please, no links or extensive explanations of what you think this is — give everyone the chance to guess.
UPDATE: The answer has now been posted below.
Twenty years ago the Voyager 2 spacecraft flew by Neptune and took this image of the Great Dark Spot on that planet. This is the last face-on view of the GDS that Voyager took with its narrow-angle camera. The
image was shuttered 45 hours before closest approach at a distance of 2.8 million kilometers (1.7 million miles). The smallest structures that can be seen are of an order of 50 kilometers (31 miles). The image shows feathery white clouds that overlie the boundary of the dark and light blue regions.
The pinwheel (spiral) structure of both the dark boundary and the white cirrus suggest a storm system rotating counterclockwise. Periodic small-scale patterns in the white cloud, possibly waves, are short-lived and do not persist from one Neptunian rotation to the next. This color composite was made from the clear and green filters of the narrow-angle camera.
For more Voyager pictures of Neptune and its satellites, check out the NSSDC website.
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You’ll have no trouble at all enjoying these stunning new images of the Trifid Nebula. This massive star factory is so named for the dark dust bands that trisect its glowing heart, and is a rare combination of three nebula types: reflection, emission and dark nebulae. With these new images from ESO’s La Silla Observatory in northern Chile, astronomers are learning more about the early stages of stellar life, from gestation to first light.
Smouldering several thousand light-years away in the constellation of Sagittarius (the Archer), the Trifid Nebula is a favorite target for amateur and professional astronomers alike. These new images shows the heat and “winds” of newly ignited, volatile stars that stir the Trifid’s gas and dust-filled cauldron; in time, the dark tendrils of matter strewn throughout the area will themselves collapse and form new stars. Full view of the Trifid Nebula. Credit: ESO
Made with the Wide-Field Imager camera attached to the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in northern Chile, this new image prominently displays the different regions of the Trifid Nebula as seen in visible light. In the bluish patch to the upper left, called a reflection nebula, gas scatters the light from nearby, Trifid-born stars. The largest of these stars shines most brightly in the hot, blue portion of the visible spectrum. This, along with the fact that dust grains and molecules scatter blue light more efficiently than red light — a property that explains why we have blue skies and red sunsets — imbues this portion of the Trifid Nebula with an azure hue.
In the bottom part of the image, in the round, pink-reddish area typical of an emission nebula, the gas at the Trifid’s core is heated by hundreds of scorching young stars until it emits the red signature light of hydrogen, the major component of the gas, just as hot neon gas glows red-orange in illuminated signs all over the world.
The gases and dust that crisscross the Trifid Nebula make up the third kind of nebula in this cosmic cloud, known as dark nebulae, courtesy of their light-obscuring effects. (The iconic Horsehead Nebula may be the most famous of these). Within these dark lanes, the remnants of previous star birth episodes continue to coalesce under gravity’s inexorable attraction. The rising density, pressure and temperature inside these gaseous blobs will eventually trigger nuclear fusion, and yet more stars will form.
In the lower part of this emission nebula, a finger of gas pokes out from the cloud, pointing directly at the central star powering the Trifid. This is an example of an evaporating gaseous globule, or “EGG”, also seen in the Eagle Nebula, another star-forming region. At the tip of the finger, which was photographed by Hubble, a knot of dense gas has resisted the onslaught of radiation from the massive star.
This has nothing to do with space or astronomy, but is perhaps one of the juiciest pieces of new I have ever read. Could we one day be driving cars fueled by watermelons? Researchers say that watermelon juice can be a valuable source of biofuel, as it can be efficiently fermented into ethanol. But have no fear, using watermelons for biofuel wouldn’t cut into the amount of watermelons available for the public to eat. This research evaluated the biofuel potential of juice from ‘cull’ watermelons – those not sold due to cosmetic imperfections, and currently ploughed back into the field. Wayne Fish from the US Department of Agriculture said, “About 20% of each annual watermelon crop is left in the field because of surface blemishes or because they are misshapen. We’ve shown that the juice of these melons is a source of readily fermentable sugars, representing a heretofore untapped feedstock for ethanol biofuel production.”
The researchers conclude that at a “production ratio of ~0.4 g ethanol/g sugar, as measured in this study, approximately 220 L/ha of ethanol would be produced from cull watermelons.”
As well as using the juice for ethanol production, either directly or as a diluent for other biofuel crops, Fish suggests that it can be a source of lycopene and L-citrulline, two ‘nutraeuticals’ for which enough demand currently exists to make extraction economically worthwhile. After these compounds have been removed from the ‘cull’ juice, it can still be fermented into ethanol.
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NASA officially scrubbed the second attempt for launching the STS-128 mission. “The last half an hour or so, a problem cropped up with a fill-and-drain valve in the bottom part of the shuttle, the aft part of the shuttle, related to the liquid hydrogen,” said NASA TV launch commentator Allard Beutel. “This particular valve … gave indications it did not close when it was commanded to.”
No word yet on what might be needed to replace the valve or restore it to normal operation. NASA is currently targeting the next launch attempt for Friday at 4:22 GMT (12:22 am ET) pending a review analysis on the valve issue.
NASA only has until August 30 to launch Discovery or the flight will be delayed to mid October because of upcoming Japanese and Russian space station missions and a conflict with the Air Force Eastern Range. We’ll keep you posted.
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We’ve written about Epsilon Aurigae before, but this mysterious star is just now beginning to dim, so we wanted to remind everyone that they can be involved in real science and help solve a mystery! The variable star Epsilon Aurigae is now beginning its puzzling transformation that happens every 27 years. “That means the last time Epsilon Aurigae had an eclipse we were all rockin’ big hair and sporting shoulder pads in all of our clothes,” said Rebecca Turner, coordinator for a special project for the IYA organized by the American Association of Variable Star Observers (AAVSO). Astronomers can’t figure out why this mysterious star dims on a regular basis, so to help solve the mystery they are calling for assistance from thousands of citizen scientists.
That means you can help contribute to real astronomical research!
Since its discovery in 1821, the supergiant star Epsilon Aurigae has dipped in brightness like clockwork every 27.1 years as it is eclipsed by a very large companion object. But based on the shape of the lightcurve and the spectra that have taken of the system, astronomers can’t figure out what exactly what kind of object is eclipsing the star. Another strange feature of the lightcurve is that there is a slight brightening in the middle of the eclipse.
“The leading theory is that the secondary is surrounded by a large opaque disk,” said Turner, on the July 7 episode of the 365 Days of Astronomy podcast. “This would explain why light from the secondary doesn’t seem to be showing up in spectra. The disk seems to have a hole in the center, which would account for the mid-eclipse brightening. Current thinking is that perhaps the center of the disk is home to 2 less luminous, tightly orbiting stars. This tight orbit could create what astronomers are calling a gravitational eggbeater effect – creating that hole in the disk. Theories of a large planet falling into the stars at the center of the disk have also been introduced recently.” Sky map of Epsilon Aurigae
Epsilon Aurigae is a bright star that can be seen with the unaided eye even in bright urban areas of the Northern Hemisphere from fall to spring. But it is also too bright for most professional telescopes to observe, so this is where the public comes in.
“It’s not just amateurs with fancy telescopes and CCDs or photoelectric photometers that are needed for this experiment,” said AAVSO’s Mike Simonsen. “People with just their eyes or a pair of binoculars can contribute to understanding this weird star by observing epsilon Aurigae over the next two years and reporting their observations to AAVSO.” A diagram of the most popular model of the epsilon Aurigae system, by Jeff Hopkins:
For this project, a new website has been launched called “Citizen Sky”, and all you need are a good pair of eyes, and a finder chart, which can be found on the website. No previous astronomical experience is necessary.
The project is supported by a three-year grant from the National Science Foundation to recruit, train, and coordinate public participation in this project. What makes this project different from previous citizen science projects is its emphasis on participation in the full scientific method. Participants are not being asked simply to collect data. They will also be trained to analyze data, create and test their own hypotheses, and to write papers for publication in professional astronomy journals. Participants can work alone on all phases of the project or they can focus on one stage and team up with others.
Epsilon Aurigae is just now beginning to dim. It will remain faint during all of 2010 before slowly regaining its normal brightness by the summer of 2011.
The lead astronomer for this project is Dr. Robert Stencel, the William Herschel Womble Professor of Astronomy at Denver University. Dr. Bob, as the amateur astronomy community knows him, studied the last event in 1982-84 while working at NASA. “This is truly an amazing star system. It contains both a supergiant star and a mysterious companion. If the supergiant was in our solar system, its diameter would extend to Earth, engulfing us,” Stencel said. “The companion only makes its presence known every 27 years and is a type of ‘dark matter’ in that we indirectly detect its presence but don’t know what it is.
“To make things even more fun, we also have some evidence of a substantial mass, perhaps a large planet, spiraling into the mysterious dark companion object. Observations during the upcoming eclipse will be key to understanding this and predicting what will happen if the putative planet does eventually fall into the star,” Dr. Bob added.
Here’s a video with Rebecca Turner explaining more about Citizen Sky.
For more on Epsilon Aurigae, see this page from AAVSO Citizen Sky
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The operations team for the Lunar Crater Observation and Sensing Satellite (LCROSS) mission has discovered the spacecraft experienced an anomaly, causing it to use up a substantial amount of its fuel. According to spacecraft data, the LCROSS Internal Reference Unit (IRU) experienced a fault. The IRU is a sensor used by the spacecraft’s attitude control system (ACS) to determine the orientation and trajectory of the spacecraft. The anomaly caused the spacecraft ACS to switch to the Star Tracker Assembly for spacecraft positional information and caused the spacecraft’s thruster to fire excessively, consuming a substantial amount of fuel. Initial estimates, however, indicate that the spacecraft still contains sufficient fuel to complete the full mission.
LCROSS is scheduled to impact the lunar south pole in early October.
The team discovered the problem during a communications pass with the spacecraft on August 22, 2009. Mission operations declared a ‘spacecraft emergency’ and were allocated additional communications time on the Deep Space Network. The team conducted procedures to mitigate the problem and were able to restart the IRU and reduce fuel consumption to a nominal level. Automatic operations procedures also were implemented to minimize the possibility of another IRU anomaly from occurring while the spacecraft is out of contact with the ground.
Thankfully, since the re-start of the IRU, the spacecraft has not experienced any additional problems.
The team continues to actively assess and mitigate the situation and is in contact with the manufacturers of the IRU and star tracker to investigate the root cause of the problems. Mission managers remain optimistic the LCROSS mission can reach its successful conclusion with projected impact at the lunar south pole currently set for 4:30 a.m. PDT on Oct. 9, 2009.
LCROSS launched with the Lunar Reconnaisance Orbiter on June 18, 2009. The main LCROSS mission objective is to confirm the presence or absence of water ice in a permanently shadowed region near a lunar pole. Learn more about LCROSS and LRO here.
"Music Combines the Soul and the Heavens" by Bhavya Mittal
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This week’s featured Astro Art was created by Universe Today reader Bhavya Mittal. Bhavya calls it “Music combines the soul and the heavens,” and explains the image: “On the bottom left is the most dangerous black hole identified till now. On the top right is the Crab Nebula, and below it, as you can see, is our dear Solar System. This image shows that when you are totally engrossed in music,you really get the feel of the Universe. At least I have felt it!”
I’m feeling it too! Great image, Bhavya. Again, this new feature allows readers to share images they have created via digital editing software and other media. If you’ve got a space or astronomy-related image you’ve created and would like to share it, submit it to Nancy . And we still haven’t found nirvana yet for what to call this new feature — so if you have any suggestions, post your idea in the comments.
South Korea successfully launched its first rocket on Tuesday, but the satellite payload failed to reach its designated orbit, officials said. The rocket, a two-stage rocket, called the Naro lifted off on schedule at 5:00 pm local time, (0800 GMT). The first stage separated successfully less than five minutes after lift-off and the South Korean-built 100-kilogram (220-pound) scientific research satellite was placed into Earth orbit. But science and technology minister Ahn Byong-Man said it was not following the designated orbit, hampering communications with mission control. “All aspects of the launch were normal, but the satellite exceeded its planned orbit and reached an altitude of 360 kilometres (225 miles),” Ahn said. Continue reading “South Korea Launches Rocket; Satellite Fails to Reach Its Orbit”
Black holes are scary, and some of the most intriguing and mysterious objects in the Universe. This is probably why they are the subject of so many science fiction stories, astronomy articles, and research papers. But what is a black hole? Black holes are essentially objects in space that are so extremely massive and dense that nothing can escape their gravitational pull, including light (which is why they are called black holes). This leads to some interesting scenarios regarding the physics in the immediate area surrounding a black hole.
The theory of general relativity postulates that anything with mass curves the fabric of spacetime, and this curvature is what we know as gravity. The most popular (and highly descriptive) example to illustrate how this works is that of a rubber sheet. Imaging that you have a large sheet of stretchy rubber that is stretched out reasonably taught. This sheet is a 2-dimensional representation of the fabric of space (which has three dimensions, but for simplicity and ease of illustration we’ll use two). If you place a small marble on the sheet, it will make a small indentation in the rubber. Imagine that the marble is a planet, and if you have one of those cool glass striped marbles, it may even look much like Jupiter. Rolling a small pebble (which creates its own, very small indentation) by the marble, you may notice the pebble veers toward the indentation of the marble. Essentially, the marble is pulling the small pebble towards it because of its gravity.
Now, if you place a bowling ball on the sheet, which is much more massive, it makes a much larger indentation that would likely trap the pebble as it rolled by. The bowling ball would represent very well something like a star in this example. A black hole is all the mass of a star, but in a very tiny space, enough to indent the rubber sheet enough so that nothing you roll by the indentation of the black hole within a certain distance – no matter how fast you make it go – can escape. The area around a black hole from which nothing can escape is called the event horizon, and how big this area is depends on the size of the black hole itself.
A stellar black hole forms when a star that has a core above about 3 solar masses gets near the end of its life, and the fusion processes inside the star are no longer pushing out sufficiently against the inward pull of gravity, causing the star to implode. Once the matter inside the star is compressed to below a certain radius – named the Schwarzschild Radius after the mathematican who formulated it – a black hole is formed.
Structure of a black hole. Image Credit: NCSA
Supermassive black holes are those that form at the center of galaxies, and they may range in the billions of solar masses. For example, the supermassive black hole at the center of the Milky Way has a mass of about 40,000 Suns, and the matter that surrounds it – called the ‘accretion disk’ – is a whopping 4 billion Suns. How do supermassive black holes form? Here’s an excellent, detailed article on supermassive black holes that goes over some of the competing theories about their formation.
Black holes come in different sizes depending on their mass. For example, if the Sun were to become a black hole (it won’t, though, because it’s core is far too small) the radius of the black hole would be about 3km (1.86 miles). If, through some weird set of circumstances, the Earth were compacted into a space smaller than its Scwarzschild Radius, the black hole would be roughly the size of a peanut.
At the center of a black hole lies what is called a singularity, where the mass of the black hole is compressed to a volume of zero, and the ability for general relativity to describe what is happening here breaks down.
How do we know black holes exist, if they don’t emit any light? Evidence for stellar black holes comes from observing their interactions in binary systems, and supermassive black holes can be observed using X-ray telescopes, as well as through the gravity they exert on the stars in a galaxy.
To learn more about black holes, there are quite a few resources on the web. For starters, Hubblesite has an excellent encyclopedia, as does Stardate.org. You can also check out the rest of our section on black holes in the Guide to Space, or listen to the multiple Astronomy Cast episodes on the subject, like Episodes 18, or the questions show on Black, Black Holes.
Posted for your enjoyment: Just hours before the scheduled launch of the STS-128 mission, NASA TV played a message from comedian Stephen Colbert, namesake of the Combined Operational Load Bearing External Resistance Treadmill (COLBERT). The treadmill is on board space shuttle Discovery, which will launch at 5:36 GMT (1:36 EDT) Tuesday morning, heading to the International Space Station for a 16 day mission. As of this writing, Discovery’s external tank has been loaded with about 500,000 gallons of liquid hydrogen and liquid oxygen in preparation for the launch. This will be Discovery’s 37th mission to space and the 30th mission of a space shuttle dedicated to the assembly and maintenance of the International Space Station.
UPDATE: The launch was scrubbed because of stormy weather. NASA will try again at 5:10 GMT (1:10 a.m. EDT) Wednesday. The most recent forecast calls for a 70 percent chance of acceptable conditions at that time.
Spaceflightnow.com will also be hosting a live webcast with Miles O’Brien, David Waters and former astronaut Leroy Chiao starting at 9 p.m. EDT Monday evening.
