Universe Today

November 29, 2007December 26, 2015 by Fraser Cain

Voyager 2 is About to Cross the Termination Shock

NASA’s Voyager 2 spacecraft is about to cross another milestone on its long journey leaving the Solar System. According to researchers at the University of California, Riverside, the plucky spacecraft is about to pass through the “termination shock”; the point at which the Sun’s solar wind slows down to subsonic speed.

According to UC Riverside researcher Haruichi Washimi, the spacecraft will cross the termination show in late 2007-early 2008. This research will be published in the December 1st edition of The Astrophysical Journal.

As you probably know, there’s a blast of particles coming from the Sun at all times. This stream of charged particles is called the solar wind, and it’s moving at supersonic speeds when it leaves the Sun.

At a certain region of space, between 11 and 13.5 billion km (7-8.5 billion miles) from the Sun, this solar wind is decelerated to less than the speed of sound because of interactions with the interstellar wind that permeates the Milky Way.

Once Voyager crosses the termination shock, it’ll be in the outer heliosphere. Actually, though, it’s going to have to cross the termination shock multiple times. That’s because this line fluctuates inward and outward depending on the strength of the solar wind.

Washimi’s calculations predict that the spacecraft will pass through the shock later this year, and then again in the middle of 2008.

The final stage in the Voyagers’ journey will occur when they reach the heliopause; the boundary where the interstellar medium completely halts the solar wind. After that, they’ll be out of the Solar System, and just traveling out into the galaxy.

Original Source: UC Riverside News Release

November 29, 2007December 26, 2015 by Fraser Cain

Hubble’s View of M74

During many holidays, the folks working on NASA’s Hubble Space Telescope try and find an image that captures the essence of the celebration. We’ve seen Christmas Tree clusters and spooky nebulae. To show their holiday spirit, the Hubble folks have released this beautiful image of the spiral galaxy M74. It’s a stretch, I guess, but wow, what a picture.

From the original Hubble news release, here’s how they describe the photograph.

Hubble has sent back an early Christmas card with this new NASA/ESA Hubble Space Telescope image of the nearby spiral galaxy Messier 74. It is an enchanting reminder of the impending season. Resembling glittering baubles on a holiday wreath, bright knots of glowing gas light up the spiral arms; regions of new star birth shining in pink.

Messier 74 is one of the best examples we can see of a “grand design” spiral galaxy, much like our own Milky Way. In the case of M74, it’s conveniently facing face on, so we can see intricate details in all parts of the galaxy’s structure.

The bright pink areas in the spiral arms are huge, short lived clouds of hydrogen gas glowing from the newborn stars inside them. The dark dust lanes that extend out along the spiral arms contain a new generation of blue stars.

M74 was first discovered by the French astronomer Pierre Mechain in 1780, and then added to Charles Messier’s famous catalogue of deep sky objects. Of all the objects in the catalogue, it’s one of the faintest, and has been nicknamed “The Phantom Galaxy” by amateur astronomers trying to spot it in their telescopes.

So thanks Hubble, feel free to celebrate any holiday, celebration or random even you like. Just keep the pictures coming.

Original Source: Hubble News Release

November 29, 2007December 26, 2015 by Fraser Cain

Newborn Star Blasting Out Powerful Jets

It’s always exciting to see an idea in theory verified with real observations. For the first time, astronomers have observed a theoretical stage in stellar evolution, when a star’s envelope is beginning to flatten and collapse, and streams of gas are escaping out. New observations by NASA’s Spitzer Space Telescope have spotted a young star right at this stage, blasting out material in powerful jets.

The new research will be published in the December 1st edition of Astrophysical Journal Letters. It provides observational evidence to this specific stage in the currently accepted model of stellar evolution.

Researchers from several universities observed a newly forming star called L1157, located about 800 light-years away in the constellation Cepheus. The star is only 10,000 years old, and still has a million years or so to go before it ignites as a star like our Sun.

New stars are born out of vast clouds of cold gas and dust. As the collective gravity of the gas pulls inward, the whole collection starts to spin. As the star grows in the middle, it spins faster and faster, and a disk of planet-forming material forms around it. Powerful jets fire off from the top and bottom of the star to relieve its accumulating pressure. Eventually the envelope of material falls onto the spinning disk, and the jets halt.

Here’s the problem in watching this process: dust. Newborn stars are surrounded in a halo of dust that visible light telescopes can’t penetrate. Fortunately, the infrared view of telescopes like Spitzer can see right through the dust, to learn what’s going on inside.

The twin jets blasting off of L1157 are huge; each one is .75 light years long. The hottest parts of the jet (seen in white in the image) are about 100 degrees Celsius (212 degrees F), but the remainder is down around zero.

The planetary disk itself is the dark band in the middle of the image, dark and hazy. In fact, it’s clogged with so much dust that not even Spitzer can see through it.

Original Source: NASA/JPL/Spitzer News Release

November 28, 2007December 26, 2015 by Fraser Cain

Neutron Star Seen Hurtling Out of the Milky Way

Like a baseball struck by a bat, there’s a neutron star out there that’s going, going, gone. Discovered using the Chandra X-Ray Observatory, the neutron star appears to be the result of a lopsided supernova explosion. It’s now hurtling away from the Milky Way faster than 4.8 million km/h (3 million mph). And it’s never coming back.

Astronomers think that the Puppis A supernova remnant was created about 3,700 years ago when a massive star detonated in a supernova explosion. Instead of exploding evenly, it was one-sided. A blast of material went in one direction, and the resulting neutron star was given a powerful kick in the opposite direction – like a natural rocket.

The neutron star’s position was measured in December 1999, and then again in April 2005. Based on the distance that it had moved, astronomers were able to calculate its velocity. With that kind of speed, it should be easy to spot, but it’s so far away that the difference is quite tiny from our vantage point. It’s impressive that Chandra was able to make the observation at all.

A detailed composite optical/X-ray image of the region near the neutron star shows clumps of oxygen drifting away from what is thought to be the centre of the explosion. The cloud is moving in the opposite direction of the neutron star.

The Puppis A neutron star is a bit of a mystery. Even the most sophisticated supernova explosion models can’t predict the speed and radiation coming from the neutron star.

“The problem with discovering this cosmic cannonball is we aren’t sure how to make the cannon powerful enough.” said Frank Winkler of Middlebury College in Vermont. “The high speed might be explained by an unusually energetic explosion, but the models are complicated and hard to apply to real explosions.”

Original Source: Chandra News Release

November 28, 2007December 26, 2015 by Fraser Cain

NASA’s Spirit Rover, Seen from Above

Just in case you needed more evidence that yes, there are robots from Earth roving around on Mars, check out this photograph. Okay, so it’s a little blurry, and you wouldn’t actually know what you were looking at unless I told you. That’s NASA’s Spirit rover, photographed by the Mars Reconnaissance Orbiter.

The blue diamond-shaped feature in the image is “Home Plate”; a puzzling region located inside the massive Gusev Crater on Mars. Spirit is a tiny dark grey speck inside Home Plate? See it? No, ah well, we’ll just have to trust the imaging folks over at NASA and the University of Arizona.

This colour image of Spirit was captured on September 27th by the High Resolution Imaging Science Experiment on board NASA’s Mars Reconnaissance Orbiter. During this period it was flying about 270 km (168 miles) above the surface of the planet.

Although you really can’t see too much of Spirit, the image helps planetary geologists put data sent back by Spirit into context.

Spirit is now driving itself to a safe, north-facing slope on the north side of Home Plate. This will position its solar panels towards the Sun, so that it can soak up as much of the Sun’s light as possible during the long Martian winter. This will let the rover continue its science operations.

Original Source: UA News Release

November 28, 2007December 26, 2015 by Fraser Cain

Lightning Storms Seen on Venus

Venus is a hostile world, with high temperatures, intense pressures, and an atmosphere with sulphuric acid. The Russian spacecraft sent to explore it succumbed in mere hours. Well, now it appears that Venus is even more dangerous than previously imagined, with lightning flashing in the atmosphere.

This latest discovery was made using ESA’s Venus Express spacecraft, currently orbiting our evil twin planet. In a recent article published in the November 29th issue of the journal Nature, planetary geologists describe the lightning storms that flare across the planet.

And these storms aren’t rare. In fact, the scientists think that Venus has more lightning activity than we have here on Earth.

The source of the lightning is different, though. Here on Earth (and Jupiter and Saturn), the electrical energy comes from clouds made up of water vapour. On Venus, however, it’s those clouds of sulphuric acid that generate the electrical charge.

The discovery was made with the Venus Express magnetometer instrument on board the spacecraft. It took measurements once a day for two minutes, when the spacecraft was closest to the planet.

With Venus Express’ primary mission now complete, scientists are expanding its mission to other scientific questions, such as trying to spot infrared radiation from lava flows on the planet’s surface. In 2010, another spacecraft will arrive at Venus: the Japanese Venus Climate Orbiter. Scientists will then be able to compare observations between the two spacecraft.

And any future landers will need to be hardened against these lightning strikes, just in case they happened to descend through a lightning storm.

Original Source: NASA News Release

November 28, 2007December 26, 2015 by Tammy Plotner

Perseus, Hero of the Night

With the Moon quickly departing early evening skies, now is the time to find a hero. Thanks to attention Comet 17/P Holmes has generated, many SkyWatchers have now become familiar with the constellation Perseus, but there’s a lot more there than just a comet! Only a few days ago, Holmes passed a wonderful bright star named Mirfak – a part of the Alpha Persei Association. Viewable with the unaided eye, but best in binoculars, this young, moving cluster is also known as Melotte 20 or Collinder 39 and is around 601 light years away. What a treat to catch a comet overlaying a star cluster!

But that’s not all… As the old year ends and a new one begins, Comet Holmes will sweep round to visit with Messier 34. At a little fainter than magnitude 5, you might be able to spot this 1400 light year distant star cluster as a hazy patch with just your eyes, but its full-moon size will make it a special treat in binoculars as Holmes passes it by!

As Comet Holmes continues to spread and dim, it will round its orbital turn and head towards a great variable star – Beta Persei. For readers, the “Demon Star” – Algol – is a familiar target, but what a treat to catch this eclipsing variable with the the comet by the last week of January 2008! Keep watching this 93 light year distant star, because as regular as clockwork – every 2.867 days – it will drop from magnitude 2.1 to magnitude 3.4 in matter of hours. To calculate Algol’s changes for yourself, try using this great interactive tool provided by Sky & Telescope: The Minima Of Algol. How fun to watch an eclipse that happens on such a regular basis!

But don’t stop watching just yet! While the comet will probably dim to telescope only range by mid-February, it’s going to slide its way past NGC 1342! This small, compressed, open cluster of stars is around 6.5 magnitude and well within binocular and small telescope range. Still not enough? Then hang on as Holmes continues takes a run for the west coast and slides by NGC 1499 – the “California Nebula” around the first week of March! If you’re able to view under very dark skies, the California Nebula can be seen unaided and in binoculars, but its low surface brightness makes it tough for a
telescope. What a great opportunity for astrophotographers!

Isn’t it time to make Perseus your hero?

November 28, 2007January 24, 2021 by Fraser Cain

Astrosphere for November 28th, 2007

For your space photo, here’s a cool image captured by Gob332. It’s some star trails behind the branch of a tree.

The New York Times has a fascinating look at the space game Eve: Online. When I get tired of World of Warcraft, I’m sure I’ll give this a look.

Why explore space? The Bad Astronomer tells you why. Oh, and he’s also giving away a book.

When there’s private space travel, there’ll be space travel agents.

Remember that cool exoskeleton in Aliens? Reality is catching up fast.

Solar? Bio-fuel? Old technology ideas. Check out these cutting edge alternative energy concepts.

Pamela continues to debunk the speculative stories coming out of New Scientist. This time, that there’s an alternative universe poking through a void in space.

Chair Force Engineer shares his list of technologies that need to be developed for a spacefaring society.

November 28, 2007December 26, 2015 by Tammy Plotner

Have a Very Martian Christmas

There will never be a better time to ask Santa for a telescope than this Christmas! Over the last few weeks the planet Mars has doubled in brightness… and for every minute that passes… Earth and Mars get about 590 kilometers closer! Closer, that is, until December 18 when our separation will be about 88.5 million kilometers apart.

Like a cosmic present, the Red Planet will reach opposition on December 24 when it will be exactly opposite the Earth from the Sun and visible from dusk til’ dawn. At around twice the size of Luna and over 230 times further away, Mars will never appear as large as the Full Moon, but it will outshine the rest of the stars in the sky for a short time. What a wonderful holiday treat for even a small backyard telescope!

Don’t be disappointed if the view doesn’t look like a Hubble image. The average telescope will reveal Mars’ soft orange globe, dark mottling and a wink of a polar cap with steady seeing. You might even spot the blue-tinged haze of a carbon-dioxide atmosphere. If you view Mars on several different occasions at various times, you’ll soon learn to spot surface markings. Remember to be patient!

The best views come during a moment of steady seeing and too much magnification can harm the view. Some good advice is to wait until Mars is reaching culmination (its highest point) and make sure your telescope has reached outdoor temperature. Begin with the lowest magnification possible and work your way up to what the sky will allow. Don’t just take a peek and walk away! Stay and watch for awhile…

Sketching is a good way to train your eye to see more details and provides you with your own observing record to compare with photographs of features. Try using great on-line interactive tools like this one from Sky & Telescope, Mars: Which Side Is Visible?

SkyWatchers aren’t the only ones taking advantage of the Mars’ approach! In August 2007 NASA launched the Phoenix Lander and its due to reach Mars in May 2008 where it will join Spirit and Opportunity. When you look at Mars, think of what the future might bring! Less than four decades ago, mankind made the monumental achievement of standing on the lunar surface in around three days.

Now missions like the Mars Pathfinder arrive at an even more distant world in seven months. According to NASA, mankind will soon be heading to the Moon “for extended periods of time, astronauts will search for resources and learn how to work safely in a harsh environment — stepping stones to future exploration.” To Mars; “Robotic missions have found evidence of a watery past, suggesting that simple life forms may have developed long ago and may persist beneath the surface today. Human exploration could provide answers to some profound questions.” and Beyond; “As humans and robots work together exploring the moon and Mars, NASA spacecraft will continue to send back scientific data from throughout the solar system, laying the groundwork for potential human journeys.”

Perhaps one day future astronauts will be wishing us a “Very Martian Christmas”!

November 27, 2007December 26, 2015 by Fraser Cain

New Images of the Martian Moons: Phobos and Deimos

With a fleet of spacecraft orbiting Mars, and rovers crawling across its surface, there’s a flood of images of the Red Planet. It’s nice to know the scientists working on those missions can take the time to look elsewhere every now and then. So today, let me present to you some images of the Martian moons: Phobos and Deimos.

The two images of the Martian moons were captured by the Compact Reconnaissance Imaging Spectrometer for Mars on board NASA’s Mars Reconnaissance Orbiter. Both images were captured while spacecraft was over Mars’ night side, and the ground below was dark.

In order to reorient away from Mars to view the moons, MRO had to turn off its normal nadir-viewing geometry.

The image of Phobos (on the top) was captured on October 23, and shows features as small as 400 metres (1320 feet) across. The image of Deimos was captured on June 7, and shows features as small as 1.3 km (0.8 miles) across.

Phobos is only 21 km (13 miles) across, and orbits Mars once every 7 days, 39 minutes. Because the moon orbits Mars faster than it rotates, Phobos would appear to travel backwards across the sky from an observer on the ground. This is just an illusion, though. Even though it’s tiny, Phobos orbits so closely that it would appear to be 1/3rd the size of our own moon in the sky.

Deimos is even smaller – 12 km (7.5 miles) – but it orbits more distantly than Phobos. It takes 1 day, 6 hours and 17 minutes to orbit the planet. Deimos isn’t large enough that you could make out any features from the surface of Mars. Instead, it would just look like a bright star in the night sky.

The first ever spacecraft observations of the Martian moons were made by Mariner 9 and the Viking Orbiter spacecraft. They found the moons to have very low reflectivity, and appeared to be similar in structure to carbonaceous chondrite meteorites. This led to the commonly held view that the moons are captured asteroids.

Original Source: MRO News Release