2014年8月31日 星期日
Space Shuttle and Space Station Photographed Together
NASA New Horizons Has Decided To Change Astronomical Definitions
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Confusing Orion PR From NASA
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Hayabusa 2 complete, ready to begin its journey to asteroid 1999 JU3
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2014年8月30日 星期六
The Starry Sky under Hollow Hill
2014年8月29日 星期五
The Wizard Nebula
NASA Opens Media Accreditation for Orion Move in Preparation for First Flight
August 29, 2014
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The Pivotal Discovery You’ve Probably Never Heard Of
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The Rise and Fall (and Rise and Fall) of Planetary Exploration Funding
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NASA Probes Studying Earth’s Radiation Belts to Celebrate Two Year Anniversary
August 29, 2014
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The Birth of the Modern Universe
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Sparks Fly as NASA Pushes the Limits of 3-D Printing Technology
August 28, 2014
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Hubble Looks at Light and Dark in the Universe
Mississippi and Louisiana Students Get Out-of-This-World Start to the School Year
August 29, 2014
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The Closest Known Exoplanet? Maybe…
In 1992, the first planets outside the solar system were discovered, orbiting the dead cinder of a supernova. Three years later, 51 Peg was found, the first exoplanet orbiting a Sun-like star. Now, after a decade of searching, we have a roster of nearly 2000 such planets, alien worlds circling alien stars.
They come in many varieties, with some being huge, Jupiter-like behemoths, and others far closer in size to our own hospitable planet. We’ve found them around distant stars hundreds of light years away, and some much closer.
And that brings us to a newly-found planet just announced: Gliese 15Ab. It has a mass of about five times Earth’s, which is interesting in and of itself; that makes it a super-Earth, if you will, a planet bigger than us but perhaps not quite massive enough to gravitationally attract a thick atmosphere. We don’t know much about what it’s like, but it’s probably not a gas giant.
But that’s not the interesting bit. The interesting bit is that its host star, Gl 15A, is a mere 11.7 light years from Earth. It’s one of the 20 closest stellar systems known, making GL 15Ab quite possibly the closest known exoplanet!
Gliese 15 is a binary star, two cool, dim red dwarfs orbiting each other. Red dwarfs are the most common type of star in the galaxy, but they’re so intrinsically faint that not a single one is visible to the naked eye; you need a telescope to see them. The closest star to the Sun we know of, Proxima Centauri, is only 4.2 light years away and even then too faint to see without using at least good binoculars.
Gliese 15 A and B (as the two stars are called, or just Gl 15A and B for short) orbit each other at a distance of about 22 billion kilometers, which is five times the distance Neptune orbits the Sun, so they’re pretty far apart. The planet discovered has a very tight orbit around the brighter of the two stars, Gl 15A, circling it a mere 11 million kilometers out. That’s close. Even though the star itself is a dim bulb, the planet is so near to it that it’s heated to at least the boiling point of water, and possibly hotter.
Gl 15Ab was found using what’s called the Doppler shift (or reflex velocity) method. Because the planet has significant mass, as it orbits its parent star in a big circle, the star itself makes a smaller circle every orbit, too. They actually each orbit their mutual center of mass, called the barycenter, like two kids facing each other, holding hands, and swinging each other around. If this sounds familiar, I just wrote about this recently because Pluto and its largest moon, Charon, do the same thing, and this was seen by the approaching New Horizons space probe.
We don’t actually see the star and planet move, but as the star approaches us in its orbit its light gets slightly blue-shifted, and as it moves away the light red shifts. The change is incredibly small, but the team of astronomers used the huge Keck 10-meter telescope with an extremely high-resolution detector. Their observing campaign has gone on for 11 years, enough to detect the planet pretty well. To be clear, they didn’t see the planet directly; they only saw its effect on the star. But this method has proven out many times, and is quite reliable.
The amount the planet can tug on its star depends on its mass, which is how they found the planet to have 5.35 ±0.75 times the mass of Earth, and by measuring the period of the oscillation determined its year to be just 11.44 Earth days long. That’s how they know it orbits the star so closely; that’s a short year!
We’re still new at all this, the finding of alien worlds. But we’re pretty good at it. We know of enough to start looking at them statistically, as a group, able to make some solid extrapolations. Given what we’ve seen so far, we think there are billions of planets in our galaxy alone. Billions! It’s like a Star Trek fever dream come true.
Given those odds, it’s not terribly surprising to find a planet so close to home. I’ll note that this planet isn’t technically confirmed; that is, also found by another team of astronomers or also seen using other methods (like undergoing transits). Still, this observation looks pretty solid, and if so this makes it one of if not the closest known exoplanets. A handful of other planet candidates have been found that are closer, but none is confirmed. There are fewer than 30 known stars and brown dwarfs (substellar objects that are similar to stars but smaller) closer than Gliese 15; many are in multiple systems, binaries or trinaries, so it’s entirely possible we’ll find and confirm a closer planet still.
But even with all that, this goes to show that the sky is likely filled with planets, and many of them are pretty close to us in a cosmic sense. It also shows just how hard it is to find them! 11 years of searching with one of the largest telescopes on Earth, and it was still a difficult task. But we’re getting better at this. If there are more, closer planets out there, we’ll find ‘em.
Tip o’ the warp nacelle to Dan Vergano.
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2014年8月28日 星期四
Messier 20 and 21
Back on the Rails with OSETI
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NASA's Spitzer Telescope Witnesses Asteroid Smashup
August 28, 2014
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NASA’s Big Rocket a Step Closer to Reality
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House members seek details on SLS/Orion schedules and spending
A day after NASA announced that the first SLS may not be ready for launch until as late as November 2018, two key members of the House Science Committee asked NASA for details on both the schedule and funding levels of the SLS and Orion programs.
In a letter released by the committee Thursday morning, [...]
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Canadian Mars Analogue Mission: Field Report, Week 2
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Artist Concept: Space Launch System Takes Flight
Congress and GAO Have Doubts About SLS Costs
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Commercial Crew Program Poll
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ISS Daily Summary Report – 08/27/14
August 28, 2014 at 01:05AM
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2014年8月27日 星期三
Milky Way over Yellowstone
With an SLS slip looming, one senator wants to keep NASA’s budget “on track”
An announcement Wednesday by NASA that the first launch of the agency’s Space Launch System (SLS) heavy-lift rocket could slip by nearly a year has led one key senator to suggest the program needs some budgetary help.
NASA announced Wednesday that the SLS passed its Key Decision Point C (KDP-C) review, an assessment of the [...]
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Selling SLS: Smoke and Mirrors - and Jedi Mind Tricks
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JSC's Girl Robot Lost Competition Due to Broken WiFi
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NASA Completes Key Review of World’s Most Powerful Rocket in Support of Journey to Mars
August 27, 2014
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The Slate Plus Doctor Who Inaugural Podcast
[Note: Extremely mild spoilers below. I figure I might as well warn you.]
As an unapologetic and enthusiastic Doctor Who fanboy, I’m really happy that the new series has started up. We’re in Season 8 now, with Peter Capaldi now (metaphorically) filling the Doctor’s fez. The first episode just aired, and I thought it was pretty good. I even tweeted it:
So it’s official.
The Hive Overmind at Slate asked if I’d like to do a podcast with various Slate-sters discussing the new episodes of Doctor Who as they air. I said yes—duh—and the first one is now online. I spent about an hour talking Whovianicity with Slate ’s Outward editor and culture critic June Thomas. We talk Clara, Capaldi, robots, Silurians, and why I thought the regeneration was handled pretty well. We also had some fun with a certain locking of lips shown in the episode as well.
Fair warning: The podcast is part of Slate Plus , which is a premium subscription service. It’s five bucks a month, and provides all kinds of fun added content; I’ve written about it before. There’s a lot of great stuff there on top of the usual great stuff at Slate , so I heartily recommend signing up.
If you need another reason, we’ll have a new Doctor Who podcast every week during the season. So join in and be a part of the fun!
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Interesting SLS Briefing Today
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NASA Telescopes Uncover Early Construction of Giant Galaxy
August 27, 2014
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NASA Holds Teleconference Today to Discuss Progress on World’s Largest Rocket
August 27, 2014
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Where does outreach funding go?
I've benefited from the STFC Small Awards but something has niggled at me over the years. After each round is complete I look at the list of funded projects and I've noticed that very few were from the area I grew up in - Yorkshire. I've been meaning to check if this was just my perception or was actually a thing and I've finally gotten around to it. I have converted all the PDFs listing previous award winners between 1999-2014 into a simple data table, written some code, and started to visualise the data. Here is a heat map of UK funding scaled by the population in each region.
Map showing STFC Small Award funding between 1999-2014 scaled by population in each UK region.
These data show that the North East and Yorkshire don't get an equal share of physics outreach funding. It is a little surprising that Leeds - the UK's 3rd largest city - only got 2 outreach grants over a 15 year period. Those were both for a theatre company that did national tours - none involved the university. So is this a bias in STFC? Given the make-up of the Small Award panel I really don't think so. I suspect that the bias is at the application stage with few people from the North East and Yorkshire applying.
If you are from Yorkshire or the North East and want to communicate physics, please consider applying for a Small Award. The next round closes on 9th October 2014 at 4pm BST . Go apply. - taken from Astronomy Blog (http://ift.tt/1g8FhhM)
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An Island Grows in the Ocean
Back in March I posted a Landsat 8 image of a volcano called Nishinoshima, located in the Pacific Ocean about 1,000 kilometers south of Tokyo. Up until late 2013 it was just a dinky island barely poking above the water’s surface. But then a second vent started erupting nearby, rapidly grew in size, and actually engulfed the original volcano.
It’s still growing. This new view from Landsat on Aug. 21, 2014, shows it puffing away:
It’s interesting comparing it to how it looked a few months ago; it’s clearly changed its shape. It’s not growing as rapidly as it once was, apparently, but it’s still getting bigger.
That whole area is loaded with volcanic islands forming seriously long chains across the ocean:
The pin marks the location of Nishinoshima. Of course, that map is scaled way out, covering thousands of kilometers. The original Landsat image gives you a better sense of how lonely the island is out there:
Pretty. And fascinating. It shows that our planet is active, constantly changing, constantly renewing itself. If it didn’t, we’d probably look a lot more like Mars. That’s a pretty amazing planet too, but given its lack of a thick atmosphere, no water, and chilly room temperature, I’ll take Earth every time. I like my environment habitable, even if it means some locally isolated places really aren’t.
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Testing Composite Cryotank Technology For Future Deep Space Missions
ISS Daily Summary Report – 08/26/14
August 27, 2014 at 01:10AM
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International Postcards from Space
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2014年8月26日 星期二
Competing for Dollars
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SpaceX Delays AsiaSat 6 - Just To Be Doubly Certain
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Europa: How Less Can Be More
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NASA Completes Successful Battery of Tests on Composite Cryotank
August 26, 2014
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Air Force starts search for an RD-180 replacement
Although the supply of Russian-built RD-180 engines that power the first stage of the Atlas V do not appear to be in the same level of jeopardy as feared earlier this year—United Launch Alliance took delivery of two of those engines last week—the US Air Force is starting to lay the groundwork for development of [...]
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