First Light!

This is a very cool image.  In fact, it’s hard to describe in mere words how cool this picture really is.  What you’re looking at is the first image beamed down from the Kepler space telescope, launched into orbit around the Sun (trailing Earth’s orbit) just over a month ago.  You can just imagine standing on the bridge of some futuristic spaceship and looking out onto such a scene as this.  But the really cool thing about this image is that in all probability, the first ever Earth-like planet we discover outside our own Solar System is somewhere within this picture.

Kepler’s three-and-a-half-year mission is to stare unblinkingly at this one patch of the heavens and detect the slightest dimming of any of the 100,000 target stars within it.  If they detect a brief drop in a star’s brightness, and that drop is repeated two more times at regular intervals, then there is a very good chance that the dimming of the star’s light is being caused by a planet passing between us and the star (called a transit) and blocking out a small amount of the light.

Kepler’s camera is the largest ever launched into space.  The image you see above is 95 megapixels in size, and the detectors are so sensitive that they expect to be able to discover planets that are up to 1,500 light years away, which is simply astounding.

One of the first things they plan to do is to see if they can detect a planet that has already been discovered by telescopes here on Earth.  It is a “hot jupiter” which simply means that it’s a gas giant, like our own planet Jupiter, and it orbits very close to it’s parent star—much closer than Mercury, in fact.  It’s so close that it only takes 2.5 days to complete an orbit, so the planet crosses in front of the star about three times a week, each time causing a slight dip in the amount of starlight reaching Kepler’s camera.  So we should know very soon if the spacecraft can do what it was designed to do.

Once they have confirmed that they can detect hot jupiters, the mission team will be settling in for the long haul.  While the main goal of the mission is to discover as many planets as they can of any size, the holy grail would be to discover an Earth-like planet (i.e. a planet about the same size and mass as our world) orbiting at about the same distance from its star as the Earth is from the Sun.  In other words, detecting a planet that might be capable of supporting life.  Of course, that means the transits and the resulting dips in the starlight will only occur once every 12 months or so, and since they need to detect three of these transits to confirm that the dimming is being caused by a planet, it will be at least three years before any major discoveries can be announced.

There is always a chance that they don’t discover any Earth-like planets at all, and that would be a major disappointment but, as the title of this blog suggests, we can always dream!