Weird Planets 12

Good morning! This is the 12th day of your tour, and it’s the last day! So tomorrow you can either rest up or start home, it’s your choice. Now, we do have a number of planets to get through today, so everybody buckle up and let’s get going!

The first one is 51 Pegasi b. Now, don’t ask about the name; they only gave us clues about one naming method, and have completely ignored any other methods that may have been used. Anyway, 51 Pegasi b is gigantic, about half the mass of Jupiter. Yet it completes its orbit in 4 days, so it’s tucked right in close, like so many seem to be. This was the first confirmed exo-planet orbiting a sun-like star, and that’s its claim to fame.

Here is system HR 8799. We aren’t here to see any one planet in this system, but the entire system. This was the first exoplanet system that was directly imaged. As you can see, the system contains a debris disk and 4 massive planets, at least.

Now this - and I keep asking for the name, but they never give it to me - was once called the Oldest Alien Planet. It is 12.7 billion years old, so it formed more than 8 billion years before Earth and only 2 billion years after the Big Bang. Its discovery made people start thinking that planets are very common in the universe and that life may have begun far sooner than anybody had ever imagined. I’m still waiting to hear from one of those civilizations that got started so much earlier than us.

Here we are, only 420 light-years away from Earth, at the Coku Tau-4 system. See the big dusty disk going around the star? Scientists think this system has the universe’s youngest star, less than 1 million years old. They haven’t actually found it yet, but if you look closely, you can see a big hole in that disk. That hole is 10 times the size of Earth’s orbit around the sun, and they surmise it’s been made by this planet cleaning up the dust as it rolls around its orbit.

This is Hat-P-1. Huge, isn’t it? It is 1.76 times bigger than Jupiter, but only has 1/2 Jupiter’s mass. It’s lighter than a ball of cork would be! What’s holding it together? I have no idea. Known as one of the Puffiest Planets known, it could float in water, if it could find a tub big enough.

This Super-Neptune, called Hat-P-11b, is 4.7 times the size of Earth, but has 25 times Earth’s mass. If you weighed 100 pounds on Earth, here you’d weigh 2,500 pounds. Doesn’t sound very inviting to me. And it’s puny star is 3/4 the size of our sun, and cooler. On the other hand, 11b’s orbit is so close to that star, it only takes 4.88 days to complete an orbit, and the surface temperature is around 1100°F. Nope, still doesn’t sound inviting.

Now here’s a fun one. Most planets orbit in the same plane as their star’s equator. But XO-3b’s orbit is at a 37-degree angle to the star’s equator. How did that happen? The only other planet that’s been known to have such a tilted orbit was Pluto. But it got demoted to dwarf planet, and its eccentricities are of no interest anymore. So tilted orbits are an oddity. I’ve heard a rumor that one planet orbits backwards to its star’s rotation. But I don’t know where it is, or else we’d squeeze that in today, too.

Okay, watch carefully, or you’re going to miss this planet. SWEEPS-10 is only 740,000 miles from its parent star. It zips around so fast, a SWEEPS-10 year is only 10 hours long. This puts it in a classification called Ultra Short Period Planets. Those are the fastest planets, where their orbits last less than a day.

Take a good look, this is the last planet of the day, and of our tour. COROT-exo-3b is the densest exoplanet known to man at this time. As you can see, it’s about the same size as Jupiter, but it’s mass is 20 times Jupiter’s. That makes it about twice as dense as lead. But it might not even be a planet. Scientists are also considering the possibility that it’s a brown dwarf, or failed star.

Please watch your step as you disembark. Thank you for taking our tour, and for sticking with it for the entire 12 legs. I know the tour is called ‘Weird Planets’, but actually, this was only a sampling. If we had tried to show you all the weird planets out there, we could be at it for years. Have safe journeys home!

[At last! I don’t know what I’ll be doing next week, but it will probably have nothing to do with planets, weird or not!]

https://www.nasa/gove/feature/jpl/20-intriguing-expoplanets

www.space.com/159-strangest-alien-planets.html