Archives for posts with tag: exoplanets

In 1584, the philosopher Giordano Bruno speculated that the Universe might be full of planets just like our own. For daring leaps of the imagination such as this, the Church duly branded him a heretic, rewarding him with imprisonment and a fiery death at the stake.

Today, we went one step further to proving him right. At a press conference earlier today, astronomers announced the discovery of two planets the same size as the Earth. These are the smallest planets ever discovered outside our solar system and the first definitive proof that worlds on a similar scale as our own exist.

The planets, Kepler 20-e and Kepler 20-f, are very close to their parent star, and therefore too hot to bear any real similarity to our home world. The news comes hot on the heels of the discovery of a planet in the “habitable zone” around a star, where it is possible for water to exist in liquid form. We are now hot on the trail of a planet that meets all the basic criteria for supporting life.

The discovery comes via Kepler: a space telescope that is surveying thousands of stars in a small area of the sky, roughly in the region of the Summer Triangle. It records the light emitted from each of the stars over time, playing close attention to any slight dips in brightness. These dips may indicate a planet moving in front of the star and momentarily blocking its light. Kepler’s systematic approach has revolutionised the science of planet hunting. To date, with just over a year’s data processed, it has found over 1,200 candidate planets.

It is surely only a short time now before a small Earthlike planet is discovered that is just the right distance from it’s parent star to support life. Who knows what may be discovered in the future about these small, watery worlds? We live in hope.

Tonight I am performing cutting-edge science. I am searching for planets revolving around stars some quadrillions of kilometres from here. My equipment? A laptop and an Internet connection. The cost? Just a bit of my time. The possible benefit? Contributing to discovery of entirely new worlds.

On December 16th, a new project – Planet Hunters – was put online. The aim is simple. You are given a whole series of light curves (graphs) from different stars, and your mission – should you choose to accept it – is to identify anything that might indicate a planet crossing in front of its parent star. It’s easy to learn. In a few minutes you can be searching for far-away planets like an expert.

Planet Hunters uses data from a satellite known as Kepler, whose job it is to study hundreds of thousands of stars over an extended period, looking for signs of planets crossing in front of their parent stars. Planets are very dim compared to stars, so they are almost impossible to detect visually. However if they happen to cross in front of a star, the light from that star decreases momentarily. This decrease can be picked up by powerful telescopes and it is these occurrences that Kepler is keeping a lookout for.

That’s where we citizen scientists come in. Many of these small drops in brightness are not easily detectable by computers. Humans are good pattern recognisers, so we can often see anomalies that a computer might not recognise. Searching through the light curves for transiting planets is a bit like finding a needle in a haystack. The planet, the star and the Earth need to line up exactly, so only a small percentage of stars are likely to show anything of interest, even if they have planets revolving around them. If enough stars are sampled however, new planets will certainly be discovered. Some scientists reckon that Kepler will quadruple the number of exoplanets known to us. We currently know of 700 planets revolving around stars other than our sun.

What hit me about searching were the many different types of light curves available. Many stars are relatively uniform, but others show complex variations and rapid fluctuations. The picture below gives you an indication of some of the star patterns I came across today.

So far in my searches I have come across a few patterns that may indicate a planetary transit. The software permits you to tag and highlight possible candidates. The same pattern is shown simultaneously to other users, so that comparisons can be made and observation errors reduced. If many people are tagging the same feature, then it is likely that something interesting is going on. Having us “citizen scientists” involved is of huge benefit to the real scientists,who would otherwise need to sort through a deluge of data.

Here are my 4 best candidates from my searches so far. They may turn out to be nothing of importance, but in any case for a few hours searching it’s been a fascinating introduction to the world of planetary discovery.

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