Kepler

Thank You Kepler! Thousands of New Exoplanets Now Confirmed

Posted on by Chris McMahon

The number of new confirmed exoplanets – planets located outside our own solar system – continues to grow at an impressive rate.

A massive amount of data is collected by space-based telescopes, which has to then be analysed and verified by astronomers. In the largest single announcement yet, NASA scientists have released information on 1,284 new verified planets, pared down from 4,302 potential candidates. When only decades ago there was not a single verified exoplanet, that number becomes staggering.

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This announcement more than doubles the number of confirmed planets identified by the Kepler space telescope. And with every new verified planet identified, the odds of identifying a true Earth-analogue increase.

Before Kepler was launched, astronomers had no idea how common planets really were. Now it is thought that there are likely to be more planets than stars. When you realise there are billions of galaxies, each with millions of stars, that’s a lot of planets! Even if the chance of life was extremely low, the likelihood of life, possibly even intelligent life out there somewhere starts to look good.

Missions like Kepler, combined with new technologies for getting actual pictures, spectrographic analysis and thermal maps of exoplanets (check out this post on capturing planetary snapshots), all point to some very exciting discoveries in the not-so-distant future.

Of the newly identified Kepler planets, around 550 could be Earth-like rocky planets. Nine of these orbit in their sun’s habitable zone, now making a total of 21 confirmed exoplanets in the so-called ‘goldilocks’ zone where liquid water can exit on the planet’s surface, allowing the potential for the formation of life as we know it. Two of these habitable zone planets are in the Tau Ceti system (see here). The potential for life on one of these planets is explored in my novel The Tau Ceti Diversion, due to be launched on September 1st 2016! Read more about what happens in the story here!

Kepler truly is the workhorse of planet-finding. Of the 3.200 exoplanets identified to date, more than 2,325 of these were discovered by Kepler. Launched in March 2009, Kepler spent four years monitoring the same patch of sky – some 150,000 stars – watching for the telltale tip in a star’s brightness that indicates a transiting planet.

Let’s hope that Kepler, and other missions like it, continue to increase our knowledge of exoplanets far into the future.

 

Capturing our First Planetary Snapshots

Posted on by Chris McMahon

 

Kepler has confirmed more than 1000 planets outside our solar system, but so far only a few of Earth-like size and in the habitable zone — rocky planets with just the right temperature for liquid water. And none of those potential Earth-analogues have been observed directly, but through the interpretation of astronomical data, such as the wobble of the star, or the dimming on the star’s light due to planetary transit.

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So far, some pictures of other planets have been taken from ground-based telescopes, but those planets are large, bright and orbit far from their suns — not like potential Earth-twins which will be far smaller and orbit closer to their suns.

NASA scientists and engineers are working on two new technologies to help look for new planets, a starshade and a coronagraph, which will both work to block the light of the star, allowing the telescope to examine the reflected light of the planet itself.

This means we can not only take pictures of prospective Earth-like planets, but also use spectrographic analysis to analyse what in their atmospheres as well. This will give us clues to what might exist there. For example, evidence of plant life and animals similar to those on our Earth would show up as a series of simple signature compounds in the planet’s atmosphere: such as oxygen, ozone, water and methane.

A starshade is a type of spacecraft that actually flies in front of the telescope to block the light of the sun under observation. Despite the fact it will be only tens of metres wide, it will fly quite a bit in front of the telescope — in fact around 50,000 km away — more than four Earth diameters. Getting it into space is a challenge. It will be folded up like a super-origami prior to launch to unfurl in space,  somewhat like an unwinding spring, into to a crazy-sized sunflower. The pointed petals are crucial to its design: they control the light the right way to reduce the glare to levels where planets can be seen. The petal-fringed shape creates a softer edge that causes less bending of the light waves.

Both the starshade and the telescope will be independent spaceships, allowing them to move into just the right position for observations. The petals of the starshade need to be positioned with millimetre accuracy.

Blocking out the starlight while preserving the light emitted from the planet is called starlight suppression.

The light of a sun can be billions of times brighter than the reflected light from the planet. Our own sun is 10 billion times bright than Earth.

Coronagraphs were originally introduced in the early 20th century to study our own sun, blocking out the light from the sun’s disk to allow scientists to study its outer atmosphere, or corona; hence coronagraph. They are much smaller than the starshade, located within the telescope itself.

These starlight-blocking coronagraphs will be more sophisticated.

These new generation coronagraphs uses multiple masks as well as smart mirrors that can deform, to suppress starlight in sequential stages. There are many other challenges in delivering the coronagraph technology, including being able to suppress or compensate for the warping and vibrations that all space telescopes experience.