Goldilocks and Johannes Kepler – Searching for Planets!

Okay, so this title is slightly misleading…Goldilocks isn’t searching for planets, and neither is Johannes Kepler (the former is a fictional character and the latter died a very long time ago). But they both play their parts in trying to find planets which are similar to our own i.e. able to support life.

We should all know who Goldilocks is. But who is Johannes Kepler?

Deutsch: Johannes Kepler war ein deutscher Mat...
(Photo credit: Wikipedia)

This is the man in question, Johannes Kepler was a German mathematician, astrologer and most importantly, an astronomer. He came up with Kepler’s laws of planetary motion. The first is the Law of Ellipses (whereby the the planets move around the sun in an elliptical shape), the second is the Law of Equal Areas (determining how long it takes for a planet to orbit the sun) and the third is the Law of Harmonies (this compares the motions of other planets). If you’re interested about these laws and wish to go into more detail, click here. Maths and physics really isn’t my deal, but it may be yours!

So what’s the link between Goldilocks and astronomy?


Well just like Goldilocks with her porridge and beds, conditions have to be just right in order for a planet to be habitable. The Goldilocks zone is the common term for the habitable zone, the distance from a star where a planets surface can maintain levels of surface water, and therefore possibly contain the building blocks of life. Our own dear planet Earth inhabits the Goldilocks zone, whereas our twin (in that the planets are very similar sizes and masses) Venus, is too close to the sun, having an arid surface devoid of any life, blistering hot temperatures and an atmosphere consisting mostly of carbon dioxide. At the other side of the habitable zone is Mars, it does contain water frozen in its polar caps, but the ultra-thin atmosphere prevents any liquid water from staying put. But we’re still looking for life on the planet, and sci-fi fans (including myself) can dream of colonising and terraforming the planet, but that’s an idea for another blog post to come later.

What’s this got to do with searching for planets?

In 2009, NASA launched the Kepler observatory, a craft currently in orbit around Earth, pointed towards to constellations of Cygnus and Lyra. These constellations were chosen as they are rich in stars that are similar to our own, and there isn’t any light interference from our Sun either. The objective of this mission is to locate Earth size (or larger) planets that are orbiting their stars within the habitable zone, as well as to calculate their orbits and compare the results.

Finding planets has to take place in space, observatories on the planet will encounter too much interference from local sources and won’t be able to actually see an individual planet passing in front of a star.

Luckily, the Kepler observatory is equipped with a powerful photometer and observes stars themselves, using the transit method to detect planets. The transit method is named after the orbit of planets (the transit); when a planet passes in front of a star being observed by Kepler, there will be a periodic dimming of light levels until the planet has moved on. Using this data from the observatory, NASA can then determine the size of the planet, and see it is within a habitable zone.

So far (as of June 2013), Kepler has detected 132 exoplanets within 76 star systems. Some of these planets, such as Kepler-20e and Kepler-20f are very close in size to Earth, but are too close to their star, making them too hot for liquid water. Kepler-22b, which was discovered in 2011, shows greater promise though, it’s within the habitable zone of its star, and scientists estimate an average surface temperature of 22°C, so not bad! The downside is that it’s about 600 lightyears away, and it’s still not known whether the planet is composed of rock, liquid or gas.


As with all equipment, parts fail. And in May this year, the second of its four reaction wheels, which hold the camera steady to observe stars, failed. But don’t count Kepler out just yet, Space News reports that NASA will try to retrieve and repair the space craft in order to keep it going, whilst New Scientist also explains that Kepler could use another method of planet detection using the same equipment.

Whatever happens though, Kepler has done a mighty fine job. For anyone who’d like more information, I’d recommend tthe official NASA Kepler website for more information. Here’s the link:


Happy planet hunting everyone!


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