Universe Today

Like Earth, Mars has frozen polar caps, but unlike Earth, these caps are made of carbon dioxide ice as well as water ice. During the southern hemisphere’s summer, much of the ice cap sublimates, or evaporates directly to a gas, but leaves behind what is known as the residual polar cap. The problem is that while the winter cap is symmetrical about the south pole, the residual cap is offset by some three to four degrees. Using data from ESA's Mars Express spacecraft, scientists say two things are to blame: the Martian weather system, and interestingly, so is the largest impact crater on Mars – even though it is nowhere near the south pole.
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Meteorites and asteroids from the inner solar system could be responsible for Earth's store of precious metals such as platinum and iridium, brought to our nascent planet during the period of Late Heavy Bombardment, about 4,000 million years ago. Dr. Gerhard Schmidt from the University of Mainz, Germany, has calculated that about 160 metallic asteroids of about 20 kilometers in diameter would be sufficient to provide the concentrations of these metals, known as Highly Siderophile Elements (HSE), found in the Earth's crust. "A key issue for understanding the origin of planets is the knowledge of the abundances of HSE in the crust and mantle of the Earth, Mars and the Moon. We have found remarkably uniform abundance distributions of HSE in our samples of the Earth's upper crust. A comparison of these HSE values with meteorites strongly suggests that they have a cosmo-chemical source," said Schmidt.
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Before you dismiss this as just another photo of Centaurus A, you better look again. It's way deeper… First discovered by James Dunlop on August 4, 1826 this incredible galaxy known as Centaurus A (NGC 5128) has been tickling the imagination of astronomers since John Herschel described it as "two semi-ovals of elliptically formed nebula appearing to be cut asunder and separated by a broad obscure band parallel to the larger axis of the nebula, in the midst of which a faint streak of light parallel to the sides of the cut appears." in 1847. What makes this incredible galaxy tick? Step inside and let's find out… Click to continue…

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It's this sort of news I really did not want to wake up to. At 0927 GMT Friday morning, a fault known as a "quench" resulted in the leakage of a tonne of helium coolant causing 100 of the LHC superconducting magnets to heat up 100°C. The fire services had to be called and it was some time before engineers could access the tunnels to assess the damage. It was worse than they were expecting. Although no one was hurt and there was no danger to the public, the once-supercooled magnets were one hundred times warmer than they should be and optimal vacuum conditions had been lost. To perform repairs, the rest of the damaged sector will need to be warmed up and then slowly cooled down again, resulting in a shutdown of LHC operations for at least two months…
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Filed under: Physics | 31 Comments »

Back awhile ago I did a review on plossl eyepieces. In that article I was trying to reach for the average individual looking for a high quality eyepiece on a limited budget. This time I asked for an example of observatory quality eyepieces that I know some of our readers own and enjoy. Is there a difference between how a very expensive eyepiece behaves in average equipment as opposed to an average eyepiece? Is there a difference in how it behaves in observatory class equipment? Step inside and let's take a look… Click to continue…

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NASA's Swift satellite captured the most distant gamma-ray burst ever detected. The blast came from an exploding star 12.8 billion light-years away, near the edge of the visible universe. Swift saw the explosion on September 13 at 1:47 am EDT. But because light moves at finite speed, and looking farther into the universe means looking back in time, this means the burst occurred less than 825 million years after the universe began, or when the universe was less than one-seventh its present age. This star was probably from the earliest generations of stars ever formed. "This is the most amazing burst Swift has seen," said the mission's lead scientist Neil Gehrels at NASA's Goddard Space Flight Center.
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Cepheid variable stars have been used for years as a way to determine distance to other galaxies. The correlation between their period of variability and absolute luminosity provides a cosmic yardstick to measure distances out to a few tens of millions of light-years. Additionally, Cepheids closer to home are used as tools to investigate how the Milky Way spins. But the motion of the Cepheids in our galaxy has confused astronomers, as these neighborhood Cepheids appear to fall towards the sun. A debate has raged for decades as to whether this phenomenon was truly related to the actual motion of the Cepheids and, consequently, to a complicated rotating pattern of our galaxy, or if it was the result of effects within the atmospheres of the Cepheids. But new observations with the HARPS (High Accuracy Radio Velocity Planet Searcher) spectograph shows that the Cepheids aren't falling, and that the much debated, apparent 'fall' does in fact stem from properties of the atmospheres around these variable stars.
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It’s a rare event anyway, but this is the last time ever. Two shuttles are now sitting on NASA's two launchpads at Kennedy Space Center. Space shuttle Endeavour completed a 4.2-mile journey to Launch Pad 39B Friday morning, Sept. 19, at 6:59 a.m. EDT, and this is the first time a shuttle has stood by as a rescue vehicle. Atlantis, over at Pad 39A is preparing for its mission to the Hubble Space Telescope, currently scheduled for Oct. 10 (although there might be an problem with that date –see below). Since Atlantis won't be going to the International Space Station which would be a "safe haven" in the event of an emergency, Endeavour will stand by in the unlikely event a rescue mission is necessary. After Endeavour is cleared from its duty as a rescue vehicle, it will move to Launch Pad 39A for the upcoming STS-126 mission to the International Space Station. That flight is targeted for launch Nov. 12. This Saturday, there will be a good photo op as the Rotating Service Structures for Endeavour will be rolled back, making both the shuttles more visible. Robert Pearlman at CollectSPACE.com has a full list of the 17 times in history two shuttles sat on the launchpads, and some great pictures, too.
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Greetings, fellow SkyWatchers! Are you psyched up for tonight's Pleiades occultation? I am! While the Moon often passes near the ancient cluster, it's not often we get to enjoy such a great event so well placed at a comfortable time of the year. This weekend we'll be watching for ISS passes, reaching for the "Ring", visiting Andromeda, and taking on two new Herschel 400 studies. Time to get out your telescopes, spotting scopes and binoculars and head out into the night because…. Here's what's up! Click to continue…

Filed under: Astronomy, Observing | 3 Comments »

Several different spacecraft have exhibited unexplained changes in speed during gravity assists when flying by Earth. First there was Galileo in 1990 and 1992, NEAR, which flew by Earth in January 1998, and then Cassini in August of 1999. Rosetta — the ESA spacecraft that recently flew by an asteroid – swung by the home planet in March 2005, followed by MESSENGER in August of the same year. All these probes showed an expected change in speed during the flyby. The largest anomaly was recorded for NEAR, whose velocity changed 13 millimeters per second more than it should have. Earlier this year, a group of JPL researchers that had been working on the problem for years basically threw up their hands, saying they hoped other physicists could come up with a solution. They had concluded the anomaly was too large to be explained by known effects related to Einstein's general theory of relativity. But a new paper proposes that Special Relativity may explain everything.
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Filed under: Physics, Space Flight | 18 Comments »

According to reports, only a day after the first successful circulation of protons in the Large Hadron Collider (LHC) last week, operations at the world's largest particle accelerator had to be stopped due to a fault with a 30 tonne transformer used to cool part of the facility. The protons were not being accelerated at the time and there was no risk to safety at the LHC.

Rather than maintaining the equipment below the operational 2 Kelvin, the transformer glitch caused temperatures to rise to over 4 Kelvin (which is still cold, after all it is only 4 degrees above absolute zero - but it's not cold enough). The transformer failed after the successful anticlockwise circulation of protons on the evening of September 11th and rumours about LHC problems have only just been confirmed…
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Filed under: Physics | 23 Comments »

Be sure to mark your calendar for tomorrow night. For lucky observers in northeastern North America, eastern Canada, and western Europe, the evening of September 19-20, 2008 is your opportunity to watch the face of the peaceful gibbous Moon glide across the ancient blue beauty of the Plieades… Click to continue…

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The Jules Verne Automated Transfer Vehicle (ATV) has done its duty – it even went above and beyond its expected capabilities. But the end is nigh, and soon, on September 29 the ATV will become a fireball and burn up in the Earth's atmosphere, never to be seen again. But before it does, people in North America and Europe have the perfect opportunity to see it sail overhead this weekend in its low Earth orbit, and according to Spaceweather.com, the ATV will glow about a brightly as the North Star, Polaris. To find out when and where to look for the ATV in the evening or early morning skies, check out Spaceweather.com's great satellite tracking webpage. Just plug in your zip code and you'll be able to get tracking information for all the satellites that will be visible for the next few days. Also, Heavens Above is a great site to find tracking information, as well. So get out there and bid Jules Verne adieu. Here's some of the great things the ATV accomplished while on orbit at the ISS, and a movie of its undocking too…

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Filed under: Satellites, Skywatching, Space Station | 15 Comments »

As you know, we wanted to answer listener questions regularly, but we found it was taking away from the regular weekly episodes of Astronomy Cast. So we've decided to just split it up and run the question shows separately from the regular Astronomy Cast episodes. If this works out, you might be able to enjoy twice the number of Astronomy Cast episodes. So if you've got a question on a topic we cover in a recent show, or you just have a general astronomy question, send it in to info@astronomycast.com. Either by email, or record your question and email in the audio file.

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Black Hole Surfaces, Magnetic Field Strengths, and the Speed of Gravitons show notes.

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The Spitzer Space Telescope has spied water in a cloud of gas and dust around a nascent star. That's interesting in itself, but even more remarkable, the water is being blasted apart by the young star's laser-like jets. Spitzer's spectrometer was used to get a better look at these jets and analyze the jet's molecules. To the astronomers' surprise, Spitzer picked up the signature of rapidly spinning fragments of water molecules, called hydroxyl, or OH. "This is a truly unique observation that will provide important information about the chemistry occurring in planet-forming regions, and may give us insights into the chemical reactions that made water and even life possible in our own solar system," said Achim Tappe, of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.
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The Cassini spacecraft recently flew through the plane of Saturn's rings and took this straight-on image of the G ring, showing a bright arc of material seen here as it rounds the ring's edge, or ansa. The spacecraft also took images of the moons Mimas and Calypso (see below). In the image here, the diffuse glow at left shows the extended nature of this faint ring. The view looks toward the sunlit side of the rings from less than a degree below the ringplane. The ring moved against the background stars during this exposure, creating the star trails seen here. Cassini scientists and engineers are preparing for an upcoming flyby of the moon Enceladus on October 9. This is the second of seven targeted Enceladus fly-bys in the Extended Mission., and the spacecraft will pass through the moon's geyser-like plumes in an attempt to measure fields and particles.
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A team of astronomers has discovered the least luminous, most dark matter-filled galaxy known to exist. The Segue 1 galaxy is one of about two dozen small satellite galaxies orbiting our own Milky Way. This is a very faint galaxy, a billion times less bright than the Milky Way. But despite its small number of visible stars, Segue 1 is nearly a thousand times more massive than it appears, meaning most of its mass must come from dark matter. “Segue 1 is the most extreme example of a galaxy that contains only a few hundred stars, yet has a relatively large mass,” said Marla Geha, an assistant professor of astronomy at Yale and lead author on a paper about Segue 1.
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The Venus Express spacecraft has been continuously monitoring the planet in orbit since 2006, and scientists now have enough data to start building a complete picture of the planet’s atmospheric phenomena. They have put together a 3-D picture of Venusian winds for the southern hemisphere. It was known that the winds on Venus are extremely fast and powerful, but what was not known was their extreme variability. The winds are highly influenced by the sun, as well as an unusual and unknown mechanism that seems to re-set itself every five days.
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Here's this week's image for the "Where In The Universe" challenge. Take a look at the image above and guess where in our universe this image was taken. Extra points if you can name the spacecraft responsible for the image as well. No peeking below before you make your guess. Ready? You may begin….

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Sorry, couldn't resist that title. Astronomers studying black holes are able to "see" them due to the fact that the gas getting sucked in gets extremely hot and emits X-rays. These X-ray pulses are commonly seen among smaller black holes, but until now, had not been detected from super-massive black holes. But astronomers using the XMM Newton X-ray satellite have discovered a strong X-ray pulse emitting from a giant black hole in a galaxy 500 million light years from Earth, created by gas being sucked in by gravity. "Scientists have been looking for such behaviour for the past 20 years and our discovery helps us begin to understand more about the activity around such black holes as they grow," said Dr. Marek Gierlinski from Durham University. Gierlinski and his colleagues say this finding is the "missing link" between small and super-massive black holes.
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The Phoenix Mars Lander is working as fast as it can to dig and deliver as many samples as possible before the power produced by Phoenix's solar panels declines due to the end of the Martian summer. This image, from Sol 107 (Sept. 12 here on Earth), shows the lander has delivered a sample of soil from the "Snow White" trench to the Wet Chemistry Laboratory. A small pile of soil is visible on the lower edge of the second cell from the top. This deck-mounted lab is part of Phoenix's Microscopy, Electrochemistry and Conductivity Analyzer (MECA).
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A cooling system for the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) science instrument aboard the Hubble telescope experienced an anomaly during a restart, causing the instrument to go into safe mode. After a couple of additional restarts, the problem still persists, and a decision was made for NICMOS to "stand down" while engineers study the anomaly and allow the cooling system to warm up, which may take a couple of weeks. In the short term, this will affect planned science observations, and engineers are hoping to avoid any long term complications. At this point, if the problem cannot be fixed from the ground, it is unclear how it might affect the upcoming servicing mission, scheduled for an Oct. 10 launch.
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At the earliest moments of the Universe, there were no separate forces, energy or matter. It was all just the same stuff. And then the different forces froze out, differentiating into electromagnetism, the strong force and the weak force. Today we'll look at the problem that has puzzled physicists for generations: is there a single equation that explains all the forces we see in the Universe. Is there a theory of everything?

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The Search for the Theory of Everything show notes.

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This Hubble Space Telescope image of two spiral galaxies shows an interesting feature on the smaller galaxy. Silhouetted in front of the larger background galaxy is a small galaxy, and tentacles of dust can be seen extending beyond the small galaxy's disk of starlight. These dark, dusty structures appear to be devoid of stars, almost like barren branches. They are rarely so visible in a galaxy because there is usually nothing behind them but darkness. But here, with the backdrop of the larger galaxy they are illuminated. Astronomers have never seen dust this far beyond the visible edge of a galaxy, and they don't know if these dusty structures are common features in galaxies.
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Has this image been showing up in your email inbox, forwarded on from excited friends? Along with it may be the following words: "This is the sunset at the North Pole with the moon at its closest point. And you can also see the sun below the moon. An amazing photo and one not easily duplicated. You may want to save this and pass it on to others." It is a beautiful picture, but is it a real photo? Even though this image was even featured on the iconic Astronomy Picture of the Day website, the image is in fact a work of art by artist Inga Nielsen, who is also an astrophysics student. The image was created with a computer program, and is called "Hideaway."
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