5 Things We've Learned About Pluto So Far

This shows Pluto and Charon in real color but the colors have been exaggerated to show the compositional differences.
This shows Pluto and Charon in real color but the colors have been exaggerated to show the compositional differences.
Photo by NASA

After NASA's New Horizons probe swooped past Pluto on Tuesday morning, NASA scientists had to settle in and wait to find out Tuesday night whether the drive-by had been a success and if the probe had actually survived to do the rest of its mission — comprised of transmitting a copious amount of data back to NASA scientists and continuing to check out stuff on the far end of the solar system. While the chances were slim at this point that anything would go wrong, there was still a slight possibility, so NASA scientists waited. Then on Tuesday night the probe, which has been travelling for more than nine years on this mission, phoned home and started sending back the first tantalizing bits of new information about the last until-now-unexplored planet in our solar system. Here's what we've learned from the New Horizons probe so far. 

5. Pluto is bigger than we thought. Until the New Horizons probe buzzed by Pluto the dwarf planet was only an indistinct blob more than three billion miles away. Since it was both tiny and surrounded by atmosphere we had no way of knowing for sure how big it actually is. NASA scientists estimated that the icy brown planet was anywhere from 1,430 miles to 1490 miles across. It turns out that those betting on the higher end of things were right: Pluto is now officially measured and it's 1,473 miles across. The planet being a little larger than expected means its atmosphere is likely more shallow and scientists will have to change all of their previous educated guesses about the planet's interior. Nifty right?

4. Pluto has a heart. And it turns out the heart is broken, or at least is comprised of two pieces. Pluto's heart was shown in clear detail when the first new images of the planet were released earlier this week. Then NASA released a new photo of Pluto and its moon, Charon, showing in real but highly exaggerated color the surface of the planet and the compositional differences of different areas on the planet. The photo captured the left side of the already iconic heart in a soft peach color while the right side came in looking very blue. That implies that the heart is most likely two different features paired up into one heart shape. Or it can be Pluto the dog, as has already been gloriously pointed out. 

3. Charon looks more beat up than Pluto. NASA scientists have thought for a while that Pluto and its moon Charon were actually made of different surfaces, but the pictures being sent back show that Charon has been soundly beat up and is pocked with craters and such. NASA people don't know whether this is because Charon is just way older and has had more solar system "life experience" than Pluto or if Pluto's atmosphere is simply helping the dwarf planet hide its age — and the tell-tale craters — a little better. 

2. The new information is, of course, leading to more questions. So far we've learned that Pluto definitely has a polar ice cap — scientists thought this before but couldn't prove it until now — and that ice cap may well be made of frozen methane and possibly nitrogen, but we don't know for sure. It also turns out that New Horizons picked up a stream of ionized nitrogen coming off the planet from more than three million miles away when most scientists had expected that the probe wouldn't start picking up the ionized nitrogen until it had gotten closer than that.  We've known that Pluto's atmosphere was leaking but we didn't know it was leaking that fast and we still don't know why that's happening. The odds are good that every knew bit of info will just lead to other things scientists — and the rest of us — want to know. Grand isn't it? 

1. We're getting more information, but we're getting it super slow. Keep in mind that New Horizons is beaming back data from more than three billion miles away, so the fact that we're getting the data at all is pretty incredible. However, the actual fact of the matter is that we're getting data in but it's going at an extremely slow rate of about 1,000 bits per second. The pace will pick up when the probe shifts so that it's pointing directly back to Earth but that will only mean increasing the download speed up to 4,000 bits per second. All of this means that we'll have to settle in and get ready to wait, because NASA scientists will be getting new Pluto data to parse through for the next 16 months at least because most of the data is still on the craft. And keep in mind that the probe passed by Pluto and has continued to explore the Kuiper Belt at the far reaches of our solar system, so we'll hopefully be getting other non-Pluto information for a long time to come. Fingers crossed. 


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