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This week on SciShow Space News, we’re learning more about the side effects of space travel… from mice. Plus, we explore the most luminous galaxy!

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When the space shuttle Atlantis landed at the Kennedy Space Center in November 2009 it was carrying a crew of seven, its usual payload of equipment from the International Space Station, and some extra special cargo -- some mice. And 6 years later, we're still learning from them. 

Over 20 teams of researchers have studied these "astromice" as they are called and this week a group of European scientists say they've learned something completely new from them about the effects of weightlessness. 

Apparently, at least for mice, living in space leads to thinner skin and also more hair growth. Could it be that we've finally found a cure for balding, just go to space? Probably not. 

It all started back in August 2009 when six 8-week-old mice flew up to the ISS. Their mission lasted for 91 days -- the longest mice have ever spent in space -- though only three of them survived the trip. 

They spent most of their time with little compartments that automatically provided them with food and water, and they lived their little mouse lives like they normally would have except they were weightless and in space and probably pretty freaked out. 

Once the mice landed, the team collected skin samples from each one and repeated the experiment in their lab with a new set of mice. Everything was the same except that those mice were on Earth. And they found that the skin samples from the mice that had been to space were a lot different that those from the mice who stayed home. 

The most obvious difference was that most of the hair of the astromice was actively growing. Now of course normally some hair on a typical Earth-bound mouse will be in the growth phase at any given time, but most of it will be in some other phase of the mouse hair growth cycle. 

Now on top of that the astromice had skin that was about 15% thinner and excessive hair growth usually thickens the skin of mice. So there was definitely something going on with the astromice but we're not sure what. 

Three mice isn't exactly a statistically reliable number of subjects but the researchers point out that a study on astronauts from 1995 to 1998 found that humans tended to suffer a lot of minor skin injuries while spending prolonged periods in space. 

So as always we have a lot more to learn about what the astro-lifestyle does to our bodies, but fortunately this study was published in a brand new journal called Microgravity, the first scientific publication to be devoted entirely to the effects of living in space. 

Also in the news this week, an international group of astronomers announced that they found a new record-breaker -- the most luminous galaxy so far. This galaxy is actually one of twenty newly-discovered galaxies reported in the study, which was published last week in the Astrophysical Journal

Luminosity is a measure of power output and these galaxies are among the most powerful in the universe. Members of a class called extremely luminous infrared galaxies. These galaxies have black holes at their centers that are basically overactive, and as matter gets sucked into them the surrounding swirling disc heats up, emitting light. 

The newly-minted record holder was detected by the WISE space telescope in 2010, and shines with 300 trillion times as much light as the Sun. This galaxy turns out to be a bit of a puzzler though. Its light has taken 12.5 billion years to reach us meaning that we see it as it was only 1.3 billion years after the universe began. So scientists aren't sure how it or its fellow extremely luminous galaxies could have grown so large in such a short time.

One possibility is that they spin more slowly than we'd expect, which might allow them to absorb more matter. But we need to study more of these weird new objects if we're gonna understand them better and luckily researchers predict that about half of the most luminous galaxies in the known universe probably haven't even been observed yet, because their visible light is being blocked by interstellar dust.

So it's very likely that astronomers will find more of these super luminous objects soon, maybe even galaxies that break the new record. 

But for now I guess 300 trillion suns seems like plenty. 

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