Space and astronomy news
Gamma ray bursts are the most powerful explosions in the Universe, releasing more energy in a few seconds than our Sun will put out in its lifetime. It’s only been in the last few years that astronomers are finally starting to unravel the cataclysmic events that cause these energetic explosions.
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Questions Show #4 – Show notes and transcript
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I gazed into the astrosphere, and it gazed right back. Here’s what I found.
First, I’d like to point your attention to the Carnival of Space #3. I’ll be hosting this one here on Universe Today, so get your submissions in ASAP. If you’ve written a space-related article, and want to join the carnival, drop me an email with a link to your story. I go live with the collection on the 17th.
Pamela and I always joke about how everything in the Universe can be discovered by looking into the Cosmic Microwave Background Radiation. Now, she reports on her Star Stryder blog, you can learn about the Oort Cloud. It’s funny, because it’s true.
There are several spacecraft hurtling out of the Solar System right now. Astroprof asks, Where are they now?
Want to dedicate your life to science? Maybe you need to solve one of the 125 big questions in Science Magazine.
The Houston Chronicle is reporting that no moon digger won NASA’s Regolith Excavation Challenge. The $250,000 prize will go back into the bank, for now.
Since the twin Voyager spacecraft flew past Saturn’s moon Titan, Scientists have been excited about what its hazy atmosphere can tell us about the earliest days of our own planet. The Voyagers discovered that Titan’s atmosphere is swirling with hydrocarbons and other complex organic molecules that could be the building blocks of life. The latest findings from NASA’s Cassini spacecraft have uncovered these organic molecules floating higher in Titan’s atmosphere than scientists originally thought possible.
This latest research has been published in the May 11, 2007 edition of the Journal Science. It shows that these organic aerosols, called tholins, have been found in altitudes higher than 1,000 kilometres (620 miles) above the surface of Titan. And these molecules are formed differently than how scientists originally believed.
This inquiry is important because the Titan’s environment is thought to be very similar to the Earth’s early history, before the first life formed. A similar process could have happened here.
Original Source: SwRI News Release
Wherever humans go, our microbes go too. Astronauts on board Mir experienced this first hand. Even thought the spaceship was cleaned as thoroughly as possible before launch, years of human habitation made it a breeding ground for molds and microbes. Over time, these wee beasties can build up, and cause a genuine health concern for spacefaring humans.
A recent article on NASA’s Science website traces the history of microscopic astronauts. In one encounter, visiting US astronauts on board Mir removed an instrument panel and discovered a grapefruit-sized ball of cloudy water, which had condensed from humidity. The water couldn’t escape, so it just built up over time. Samples brought back to Earth showed it contained several dozen species of bacteria and fungi.
On board Mir, organisms were found growing on rubber gaskets around windows, on spacesuit components, copper wire insulation. Pretty much everywhere. And the International Space Station has the problem too. Astronauts have discovered patches of mold growing on a panel where they hang their exercise clothes.
NASA is working on new tools that will help astronauts be able to detect different kinds of microbes and fungi, and then choose the right cleaning compound for the job.
Original Source: Science@NASA
All right, this article from NASA is totally pandering to my Star Trek geekiness. I know I’m being manipulated, but I just… can’t… resist. According to NASA, their upcoming SIM PlanetQuest mission should be able to find Star Trek’s planet Vulcan. You know, Spock’s home?
Okay, I’ll try and put this into some kind of scientific justification. The SIM PlanetQuest is a new mission in the works at NASA. If all goes well, and it doesn’t befall the fate that struck the Terrestrial Planet Finder, it will launch into an Earth-trailing solar orbit. Once fully operational, it’ll be able to detect potentially habitable planets as small as the Earth around nearby stars.
Here’s the Star Trek angle. One of the stars that it’ll be able to detect Earth-sized planets around will be 40 Eridani, a triple star system located about 16 light-years from Earth. In the Star Trek universe, the planet Vulcan, home of Spock, orbits the star 40 Eridani A, which is part of this system. So, if all goes well, SIM PlanetQuest will be able to find an Earth-sized world, in the habitable zone around 40 Eridani A. It’ll find Spock’s homeworld, get it?
If the Terrestrial Planet Finder does get brought back from canceled status, it’ll be able to take this research to the next level, and actually search for signatures of life around any worlds which are discovered.
Original Source: NASA News Release
Astronomers have found that the cosmic wreckage left over when large galaxies collide have an unusually high amount of unseen matter in them. In some situations, these dwarf galaxies have twice the matter that astronomers would expect.
The research was done using the National Science Foundation’s Very Large Array (VLA) radio telescope to study a galaxy called NGC 5291, located about 200 million light-years from Earth. About 360 million years ago, this galaxy collided with another, and the collision sent out streams of stars, gas and dust. These streams later coalesced into dwarf galaxies that orbit the parent galaxy.
Under the VLA survey, astronomers studied three of these dwarf galaxies, and found that they have two to three times the amount of dark matter as visible matter. Astronomers don’t actually think this is the mysterious non-interacting dark matter that makes up the bulk of matter in the Universe. Instead, it’s cold hydrogen molecules which are extremely difficult to see.
This cold molecular hydrogen likely came from the disks of the galaxies, and not the haloes.
Original Source: NRAO News Release
The Universe is thought to be 13.7 billion years old. So it was quite a surprise when astronomers turned up a star that’s 13.2 billion years old. That means it formed only a few hundred million years after the Big Bang.
The star, HE 1523-0901, was discovered by the European Southern Observatory’s VLT. Astronomers knew right away that that had an old star, but the technique for dating it accurately is pretty difficult. The method is similar to radiocarbon dating, where archaeologists use the approximate quantities of carbon isotopes to measure the age of ancient artifacts.
In this situation, though, the astronomers used the VLT to measure the abundance of the various radioactive elements, like thorium and uranium. Once the star originally formed, its radioactive elements began to decay, changing into other elements. By knowing the rate of decay, and being able to measure these elements so accurately, they were able to peg the ages of the star at 13.2 billion years old. The trick was to find elements that decay at a set rate, but would still be around after billions of years of decay.
Original Source: ESO News Release
Slacker Astronomy’s Aaron Price has written up a detailed review on the state of blogging and podcasting in astronomy. Stuart from the Astronomy Blog has written up a nice review of the review.
With the recent discovery of the most powerful supernova ever witnessed, it raises the question, what will happen when the much closer Eta Carina blows up? Alan Boyle from MSNBC’s Cosmic Log finds the answer.
How do you determine the age of a star? Pamela Gay from Star Stryder (and Astronomy Cast co-host) shows you how it’s done.
Andy the e-Astronomer thinks that the golden age of astronomy surveys is coming to a close, because all the low-hanging fruit has been found. He suggests new avenues for productive discovery.
Here’s a scenario that will face many of us in the far future. You’re hurtling through the cosmos at nearly the speed of light in your spaceship when you take a wrong turn and pass into the event horizon of a black hole. Uh oh, you’re dead – not yet, but it’s inevitable. Since nothing, not even light can escape the pull from a black hole once it passes into the event horizon, what can you do to maximize your existence before you join the singularity as a smear of particles?
Physicists used to think that blackholes were sort of like quicksand in this situation. Once you cross the event horizon, or Schwarzschild radius, your date with the singularity is certain. It will occur at some point in the future, in a finite amount of proper time. The more you try to struggle, the faster your demise will come. It was thought that your best strategy was to do nothing at all and just freefall to your doom.
Fortunately, Geraint F. Lewis and Juliana Kwan from the School of Physics at the University of Sydney, have got some suggestions that fly in the face of this stuggle = quick death hypothesis. Their paper is called No Way Back: Maximizing survival time below the Schwarzschild event horizon, and it was recently accepted for publication in the Proceedings of the Astronomical Society of Australia.
When an unlucky victim falls into the event horizon of a black hole, they will survive for a finite amount of time. If you fall straight down into a stellar black hole, you’ll last a fraction of a second. For a supermassive black hole, you might last a few hours.
Due to the tremendous tidal forces, an unlucky victim will suffer spaghettification, where differences in gravity from your head to your feet stretch you out. But let’s not worry about that for now. You’re trying to maximize survival time.
Since you’ve got a spaceship capable of zipping around from star to star, you’ve got a powerful engine, capable of affecting your rate of descent. Point down towards the singularity and you’ll fall faster, point away and you’ll fall more slowly. Keep in mind that you’re inside a black hole, flying a spaceship capable of traveling near the speed of light, so Einstein’s theories of relativity come into play.
And it’s how you use your acceleration that defines how much personal time you’ll have left.
In a moment of panic, you may point your rocket outwards and fire it at full thrust, keeping the engine running until you arrive at the central singularity. However, Lewis and Kwan have demonstrated that in the convoluted space-time within the event horizon, such a strategy actually hastens your demise, and you’ll actually end up experiencing less time overall. So, what are you to do? Lewis and Kwan have the solution, identifying an acceleration “sweet-spot” that gives you the maximal survival time. All you have to do, once across the event horizon, is fire your rocket for a fixed amount of time, and then turn it off and enjoy the rest of the fall.
But how long should you fire your rocket for? Lewis and Kwan show this is a simple calculation involving the mass of the black hole, how powerful your rocket is, and how fast you crossed the event horizon, easily doable on a desktop computer.
Here’s another analogy from Lewis:
“Consider a race to the centre between a free faller and a rocketeer. Suppose they cross the event horizon together holding hands. As they cross, they start identical stop watches. One falls inwards, while the other accelerates towards the centre for a little, then swings their rocket round and decelerates such that the free faller and the rocketeer meet and clasp hands again just before hitting the singularity. A check on their stop watches would reveal that the free faller would experience the most personal time in the trip. This is related to one of the basic results of relativity – people in freefall experience the maximum proper time.”
So now you know. Even after you’ve fallen into the black hole’s event horizon, there are things you can do to lengthen your harrowing journey so that you get to experience more time.
Time to you can use to deal with your spaghettification problem.
Original Source: Arxiv research paper
When astronomers look into the night sky, almost every single galaxy is speeding away from us, carried by the expansion of the Universe. There’s one notable exception; though, the massive Andromeda galaxy (aka M31), which is speeding towards us at a rate of 120 km/s. And some time in the next few billion years, our two galaxies will collide and begin the lengthly process of merging together. Our Sun, and even the Earth should still be around, so it begs the question, what will happen to our Solar System?
Fortunately, T. J. Cox and Abraham Loeb from the Harvard-Smithsonian Center for Astrophysics have done the math in their recent paper entitled The Collision Between The Milky Way And Andromeda. In this paper, they chart out their simulation of this massive collision, and estimate some future fates for our Solar System.
Our galaxy, the Milky Way, and Andromeda (M31) together with their 40 smaller companions make up the two largest members of the Local Group of galaxies. While most galaxies are hurtling away from us as part of the expansion of the Universe, the Local Group is gravitationally bound together, and will continue to interact over the coming years.
When our Sun was born, 4.7 billion years ago, Andromeda and the Milky Way were 4.2 million light-years apart. Steadily moving together over the billions of years, they’re now only 2.6 million light-years apart and clearly headed for a collision. But it won’t be a head-on collision, the two galaxies will take swipes at each other first.
The first sideswipe will occur less than 2 billion years from now. During that first interaction, there’s a 12% chance that the Solar System might get ejected from the disk of the Milky Way, and spun out into the tidal tail of material that will stream out from the Milky Way. And there’s a remote chance, less than 3%, that the Sun will jump ship, joining up with Andromeda, and leaving the Milky Way entirely.
Since the Sun and the Earth will still be around, future astronomers could witness the collision in all its glory. Since the Sun will be steadily increasing its output of radiation, life might not be able to survive on our planet if engineers can’t figure out a way to keep the Earth moving away from the Sun.
Then the galaxies will come back together for another swipe, and then another, and eventually settle down into a gigantic swarm of stars buzzing around a common center of gravity. Currently quiet, the twin supermassive black holes may flare up, becoming active galactic nuclei, feasting on the torrent of new material that was unlucky to enter their feeding zones. Colliding clouds of gas and dust will flare up in furious regions of star formation.
In all likelihood, these interactions will push the Sun out into the new galaxy’s outer halo, pushing us at least 100,000 light years from the centre, and safely way from those twin black holes.
And 7 billion years from now, when our Sun is in the last stages of life – a red giant – and our Earth is a burned cinder, Milkomeda will have formed.
(At least, that’s what Cox and Loeb are calling it. I coined Milkdromeda in an episode of Astronomy Cast.)
This future galaxy will be a massive, elliptical galaxy, losing any remnant of its familiar spiral arms. The furious star formation will settle down, and this new galaxy will live out its remaining years, slowly using up its remaining raw stellar material.
100 billion years from now, all galaxies not bound to the Local Group will recede from vision – now traveling away from us faster than the speed of light. The concept of extragalactic astronomy will end, and Milkomeda will account for the entire visible Universe.
Original Source: Arxiv