IRA FLATOW: This is “Science Friday.” I’m Ira Flatow. Now for a little story. Once upon a time, the only planets we knew about were the ones in our own solar system. But as telescopes and techniques improved, we began to realize that there are plenty of planets to go around, that a solar system having planets may be the rule, not the exception.

And in recent years, spurred on by even better instruments and improved hunting methods, astronomers are logging an increasing list of planets that could be sort of like home. The right general size, the right distance from their star, the Goldilocks zone.

Well, this week astronomers announced the discovery of an intriguing new neighbor, and here to talk about that and other selected short subjects in science is Rachel Feltman, editor of the Washington Post Speaking of Science blog. Always good to see you around, Rachel.

RACHEL FELTMAN: Good to see you too, Ira.

IRA FLATOW: Hope I didn’t scare you away with that bedtime story.

RACHEL FELTMAN: No, not at all.

IRA FLATOW: Well, let’s talk about the discovery this week of this new exoplanet that could be sort of like Earth?

RACHEL FELTMAN: It could be sort of, but let’s not get ahead of ourselves. It’s called Proxima B and it orbits Proxima Centauri, which is our closest star. It’s a tiny little cool red dwarf about 4.25 light years away, which relatively speaking, is a stone’s throw.

It could potentially be Earth-like, but there are a lot of things we don’t know about this planet. In fact, all we do know about it is that it very likely exists. We know that it could be rocky, based on how far it is from its star and what we know about the planets that form around red dwarf stars. We know that it could be in the star’s habitable zone.

But without an atmosphere, its temperature is around minus 40 degrees Fahrenheit. It’s only within atmosphere that it would have temperatures similar to Earth. So there are all these ifs. If it’s actually rocky–

IRA FLATOW: You’re spoiling the story, Rachel.

RACHEL FELTMAN: But it’s still really cool, because it’s so close by. And it’s becoming increasingly clear that there are probably planets around most stars. And even these red dwarf stars that were so neglected are good places to look for life.

IRA FLATOW: This got a lot of press this week–

RACHEL FELTMAN: Right.

IRA FLATOW: –or of ink, as we used to say in the business. But I thought the really more interesting story was, though, that scientists have found a galaxy that is almost 100% dark matter.

RACHEL FELTMAN: Right. So most galaxies, like the Milky Way, which is kind of an average size galaxy, are about 90% dark matter. And scientists found one that is 99.99% dark matter, which basically means that it has– it’s as if somebody went into the Milky Way, and for every 100 stars, threw away 99 of them, but somehow, it’s staying together.

The gravitational forces of these stars should not be enough to keep the galaxy from tearing itself apart, and yet something keeps it together, and that thing is dark matter, and it makes up most of the galaxy.

IRA FLATOW: Now, I know, in a regular galaxy, you look at the bright stuff and you say there’s not enough of the bright stuff there to keep it together [INAUDIBLE]. But dark matter, which is all– a galaxy that’s all dark matter, how do you know it’s even there?

RACHEL FELTMAN: Well, what’s really cool is that they found it with this telescope called the Dragonfly, that is basically a bunch of telephoto lenses stuck together. Because the researchers who built it realized that these objects that are really faint and big, that are hard to look at with traditional telescopes, that telephoto lenses, like the ones you use at sporting events, are actually pretty well suited for seeing these kinds of objects.

So they just kind of put enough of the pieces together to turn it into a telescope. And while they were looking at the sky, they saw what they thought were image defects, these smudges. And once they re-examined the data and looked at them again with Keck, it turns out it’s what they think is an entirely new class of object. And they think they’re going to find a bunch more of these super dark galaxies.

IRA FLATOW: Shades of Bell Labs and cosmic background radiation.

RACHEL FELTMAN: Yeah.

IRA FLATOW: Yeah. There’s something wrong with the instrument, right? Let’s talk about NASA just found a spacecraft that’s been lost for two years?

RACHEL FELTMAN: Yeah, so it was only–

IRA FLATOW: How do you lose a spacecraft?

RACHEL FELTMAN: Well, it was so recently that we said our final goodbyes to the Philae lander off of the Rosetta orbiter. We had to finally deal with the fact that that lander was gone forever.

And now NASA has a story with a potentially happier ending for STEREO-B. It’s one of two orbiters. They’re on either side of the Earth, orbiting the sun, and they create these 3D images of solar flares and coronal mass ejections, so that scientists can better understand them.

And basically what happened is that these outlived their lifespans by several years, and so scientists had to start to prepare for an event that the spacecraft hadn’t been designed for, which was the spacecraft going behind the sun, and them not being able to communicate with it, and it having to take care of itself.

So they were trying to keep it from turning itself off in a way that would hurt it, and instead, they triggered it doing exactly that thing. So it let out a weak signal and then they didn’t hear from it again. Then they knew it was going to be behind the sun anyway. It was tumbling out of control. Its solar panels probably weren’t getting light. But they finally caught it with enough power that it sent a signal back to the Deep Space Network two years later.

The problem is that apparently they only have these really brief windows, like a few minutes at a time, where they can hope to re-establish communication and send it commands before it triggers the whole process again and does another hard reset and sends itself spiraling again. So it’s not actually clear whether they’re going to be able to regain control of it, but at least they know that it’s out there.

IRA FLATOW: That’s a really fun story. And last, researchers are asking a 5,000-year-old man, the “who are you wearing” fashion question. And they’re getting– he’s wearing a lot.

RACHEL FELTMAN: Yeah, he’s wearing an awful lot. Otzi the Iceman, who was found in 1991, is still giving us all this new information, because we keep getting better and better techniques to examine him with. And researchers just used mitochondrial DNA sequencing on the clothes he’s wearing. Because it’s clear they’re animal skins, but we had no way of telling which.

And it turns out, he is wearing at least five different species of animal. He is wearing goat skin leggings, a sheep loin cloth. His shoes were made of cow leather. His hat was made out of a brown bear. His coat was made out of goats and sheep. At least, like, four different individual goats and sheep, I think. And then his bow– his arrow quiver was made from a deer. So he got around, clearly.

IRA FLATOW: Wow. He’s sort of the MacGyver of icemen.

RACHEL FELTMAN: Yeah, and it’s really interesting, because it raises the question of, how many of these animals were domesticated? Did he hunt them? Did he trade for them? Did he make the clothing himself? But we at least have this glimpse now into the fashion sense of a 5,300-year-old man.

IRA FLATOW: Yeah. Rachel, always fascinating.

RACHEL FELTMAN: Thank you.

IRA FLATOW: Thanks for dropping by. Rachel Feltman–

RACHEL FELTMAN: Thanks for having me.

IRA FLATOW: –you’re welcome– is editor of the Washington Post Speaking of Science blog.

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