International Halley Watch

Transcription

Hi I'm Hank Green! Welcome to SciShow Space News. This week, the lesson seems to be that some things that come down to us from space are more delightful than others. First off, back on April 20th, SpaceX launched its third resupply mission to the International Space Station, delivering coffee, an experimental vegetable garden, and a whole bunch of bacteria. The bacteria were a gift from Project MERCCURI, a crowdsourced NASA program that enlisted the help of citizen scientists all over the United States to collect samples of bacteria. People collected bacteria by swabbing things like a basketball used in an NBA game, the Liberty Bell, and part of a fossilized T. rex. A little weird, maybe, but that bacteria might help us answer some basic questions about the nature of pathogenic microbes. NASA has been sending Salmonella into space since 2006. And one of the scarier things that they’ve found is that, compared to samples that stay on Earth, samples incubated on the ISS come back three to seven times more virulent. But don’t panic though! NASA’s on top of it! Biologists think this space-borne virulence may have to do with the effects of microgravity on the fluid that surrounds a microbe's outer surface. Typically, this fluid typically exerts a force, called fluid shear, that tells the microbe where in the body it's located. Using computer simulations, researchers have found that the fluid shear in microgravity is very similar to that of human intestines. So it seems that space Salmonella thinks it's in someone’s intestines, which activates genes that put it into overdrive. Biologists are thinking that messing with the pathogen's ability to detect fluid shear might be a key to creating antibiotics for it. Meanwhile, the Project MERCCURI samples have just been sent back to Earth, along with swabs from around the space station itself. And now, they'll be compared with samples that remained on the ground to study if, and how, life in space changed them. Now here’s something headed our way that may make you less anxious -- the Eta Aquarids meteor shower, which peaks this Monday and Tuesday. They've been showering down since April 19th and will continue until May 28th, but on May 5th and 6th they'll appear at a rate of about 30 meteors per hour. Wherever you are in the world, you'll be able to see them in the early morning between moonset and sunrise of Tuesday, May 6th in the constellation Aquarius. And they're going to be awesome. Traveling at about 66 kilometers per second into Earth's atmosphere, they'll leave glowing trails of burning debris in their wakes. That debris actually comes from Halley's comet, a 16-kilometer-long bit of ice and rock in a 76-year orbit with the sun. When Halley approaches the sun, as it did in 1986, it heats up and leaves a trail of debris. Earth crosses through this trail twice a year, once in May and once in October, giving us the Eta Aquarids and the Orionids. These remains of Halley should hold us over until its next appearance in the solar system in 2061. Finally, there’s one new celestial discovery that you won't be able to see, unfortunately. Last week NASA's Wide-field Infrared Survey Explorer, or WISE, discovered a star that's only 7.2 light-years away, making it the fourth-closest star to our own. If you can call it a star. It's a brown dwarf, which is sort of like a failed star that’s never achieved fusion. Brown dwarfs are bigger than planets, but not as big as other stars, and they only give off a faint bit of energy. Because of their size and dimness, they're easy to confuse with gas giants like Jupiter—and they can be hard to detect. That's why we've only just noticed the new one - even though it’s so close - using infrared readings of the sky. At only a few times larger than Jupiter, it’s the smallest and coldest brown dwarf yet discovered. But as we get better at finding these smaller, cooler brown dwarves, astronomers think we might start finding them in all sorts of unexpected places. And this might be an answer to one of the universe's great mysteries: where is all the matter that should be out there? Maybe it's hiding in plain sight, just too cold to see. Thanks for watching SciShow Space News -- especially to our Subbable subscribers. If you want more SciShow for your very own, check out Subbable.com/scishow to learn how to get a SciShow DVD with some extra behind the scenes features. Let us know if you have any questions or comments on Facebook and Twitter, or in the comments below, or if you an idea for a future episode. And if you want to keep getting smarter with us, you can go to youtube.com/scishowspace and subscribe.