Exoplanet Update

Artists impression of a "puffy" planet. A comparison to Jupiter is in the bottom right

Exoplanets just fascinate me. The fact that there are potentially millions of other planets and planetary systems in outer space just blows my mind. Planets are being discovered literally on a daily basis. In the past week almost 100 new exoplanets were discovered or confirmed by various telescopes and space agencies. So today I thought I'd talk about a few of the most interesting ones.

Corot-2b: This planet was discovered back in 2007, but a huge discovery about it's interaction with its host star has just been made. The Chandra X-ray observatory just discovered that this planet is being pummeled by X-rays from Corot-2! X-rays are not good for humans, and they are not good for planets either! This roughly 3 Jupiter mass planet is being hit by 100,000 times more X-rays than the earth gets hit with every day. These harmful rays are evaporating the gas that the planet is made of at a rate of 5 million tons per second! Now I know that sounds like a lot, but the planet is so massive that at this rate of evaporation it will still survive for over 30 billion years!

HAT-P 32b, 33b, 24b and others: These are what I like to call "puffy" planets. Puffy planets are half to one Jupiter mass in weight but two Jupiter radii or larger in size and orbit their host star on the order of days. Essentially they are really big, lightweight, fast orbiting planets. They are peculiar because one would expect the planets to be smaller either due to solar wind/X-rays stripping material from them, or just general gravitational collapse of their small amount of gas. Astronomers are currently working on models to describe such planets.

HD 85512-b: This is today's newest possibly habitable planet. HD 85512-b is orbiting a star about 3/4 the size of our sun with an orbital period of 58 days. It's technically too close to the star to be in the habitable zone, but if the planet is rocky, and has sufficient cloud cover, it could potentially be habitable. Much more work needs to be done before we will know if it has the potential to support life.

Image Credit: D. Aguilar

GRAIL

Artists impression of GRAIL

Even though the space shuttle program has ceased, NASA is still alive and active with eyes towards the moon. On Saturday, September 10th around 9am EST, NASA launched the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft from Cape Canaveral, FL. GRAIL is a set of two satellites that will orbit the moon and map its gravitational field. The moon has about 15% the amount of gravity we experience here on Earth, mainly because it is only about a quarter of the size of Earth. Understanding the moons gravitational field will help scientists understand the moons interior structure reconstruct its past. We will be able to answer questions like: Does the moon have a molten core? Why do the craters on the light side of the moon appear to be filled with solid magma, while those on the dark side do not? One interesting thing about the launch of GRAIL is its journey to the moon. A trip to the moon for the space shuttle took about 3 days, but GRAIL is going to take 3.5 months! The rocket was actually aimed in the direction of the sun, and with the help of small thrusters the trajectory will be corrected so that the satellites will reach the moon. This is called a low-energy trajectory and was done intentionally to save fuel, and to leave time for the satellites and equipment to adjust for space conditions. Think about it like this: if we hurtle towards the moon in three days, it will take a lot of fuel and energy to slow the satellites descent so they don't crash into the moon. But if instead we go the "long way around" and leisurely approach the moon, we can just float into orbit using very little fuel only to adjust trajectory. In these hard economic times, NASA is trying to save every penny they can!

Image credit: NASA/JPL/MIT