Planets! Get your red-hot planets!
One cannot have too many groundbreaking discoveries in one day. Today we have two. Not only did NASA announce the direct visual imaging of a planet orbiting the star Formalhaut, another team of astronomers announced the infrared imaging of an extrasolar system of three planets orbiting the star HR8799, about 140 light years away. The image below shows two of the three planets in the HR8799 system, and was obtained using the W. M. Keck Observatory and the Gemini North Telescope, both on Mauna Kea, Hawaii.
The HR8799 system contains three known planets, and probably several more that are too small for us to detect with existing technology. The three HR8799 worlds are all gas giants, and vary from seven to ten Jupiter masses each. All three orbit far from their primary, at 24, 37 and 67 astronomical units (AU). By comparison, Neptune orbits at 30 AU from the Sun.
This is a young system, only about 100 million years, which means these worlds are still in the throes of planetary accretion. When the Earth was 100 million years old it was still a hellscape of molten rock, blasted continually with mountains tumbling from space, including another planetoid named Thea, part of which forms our Moon. Unlike our system, the HR8799 planets won’t have the luxury of billions of years to evolve. Their hot, blue star will only last a fraction of that time.
Now we can see planets. Now we can see entire planetary systems. That means we can see the light that bounced off a planet and passed through its atmosphere (if it has one), along with spectroscopic telltales of whatever gases compose it. This is how we will first discover life elsewhere in the cosmos; not by sampling it directly, but by recognizing its effects on the atmospheres of entire worlds. Oxygen, ozone, and possibly other more interesting compounds would be a dead giveaway that something lives there and is driving the production of gases that cannot otherwise easily form. I don’t think we’ll have too many more years to wait before that discovery is made.