Exoplanets, Kepler 22b, and the speed of light

About a week ago NASA announced the discovery of yet another exoplanet (so far about two thousand has been discovered and we are discovering more every week). What was special about this exoplanet which has the name kepler 22b, was that it was the most earth like discovered to date. Its radius is 2.4 times the radius of the earth and the orbital period is about 290 days. Depending on how much atmosphere the planet has its surface temperature would be either -11C or +22C (with atmosphere similar to hours). In other words, this could potentially be a planet that we could live on, just one problem, it is 600 lights years away from us... This means that it is hard to get to... Here is my calculation.

• 600 light years is how long light travels in 600 years

• In one second light travels 300.000 kilometers or 7.5 times around the earth, or 3/4 of the way to the moon (384.000 kilometers)
• In one minute light travel 60 x 300.000 kilometers = 18.000.000 kilometers, 18 million kilometers
• In one hour light travels 60 x 60 x 300.000 kilometers = 1.080.000.000 kilometers, 1 billion kilometers
• In one day light travels 24 x 60 x 60 x 300.000 kilometers = 25.920.000.000, 26 billion kilometers
• In one years light travels 365 x 24 x 60 x 60 x 300.000  kilometers = 9.460.800.000.000, 9.5 trillion kilometers
• In 600 years light travels 600 x 365 x 24 x 60 x 60 x 300.000 kilometers = 5.676.480.000.000.000, 5.7 quadrillion kilometers.

Some distances to compare this to:

• The earths circumference is 40.000 kilometers
• The distance to the moon is 384.000 kilometers
• The distance to Mars from earth (when it is at the nearest point) is 54.000.000 kilometers
• The distance to the sun is one AU which is 1.500.000.000 or 1.5 billion kilometers 
• The distance to uranus is 2.570.000.000, or 2.57 billion kilometers
• Distance to nearest star, called Proxima centauri (which is not the sun) is 4.22 light years or 39.900.000.000.000 kilometers, or 39 trillion kilometers away

How long would it take to go to exoplanet Kepler 22b? Well, that depends on the speed of your spacecraft of course. According to wikipedia, the fastest spacecraft we have build so far is the helios probe (unmanned), which had a maximum speed of approximately 260.000 kilometers per hour or about 71 kilometers per second. If we assume that space research gets lots of money and manage to recruit clever scientists and we eventually get a spacecraft that goes more than 10 times as fast, say 1000 kilometers per second then it would take

5.676.480.000.000.000 / 1000 = 5.676.480.000.000 or 5.7 trillion seconds, which translates to 180.000 years, or about 6000 human generations. In other words, if you went not only would you have to spend the rest of your life travelling in space but your son or daughter would also have to spend their life on the spacecraft. Also your grandchild, grand grand child, grand grand grand child and grand grand grand grand grand grand grand (six thousand times), would have to live on the spacecraft. It seems likely that on the

In other words we need to find an exoplanet that is much closer and still earth-like, however, I am optimistic!

One way trip to Mars

This week the Skeptics Guide to the Universe featured a fascinating interview with Lawrence Krauss, author of "the physics of Star Trek. The interview was about space exploration and human space exploration in particular.

Lawrence argued I think convincingly that if we want to bring humans to Mars it should be a one way trip. Reason? Bringing the fuel for the home trip to mars and taking all necessary safety precautions to bring the humans back to earth alive would probably cost 10-times as much as it would cost to simply send them there and then provision them with all necessities for the rest of their life.

Would anyone do this? According to Lawrence it was more difficult to find a scientist who would not do it. We should not see it as sending people to their grave, rather, think of it as building a permanent human coloni of Mars, and it suddenly sounds quite cool.

Lawrence Krauss published most of these thoughts in an NY Times article in 2009 which can be found here.

Our tiny planet in our huge Universe

I have always been fascinated by astronomy and before I decided to go into neuroscience to study our amazing brain I had dreams about studying astronomy. I personally cannot understand how people can avoid being overwhelmed by our universe.

Our earth is a pretty big place, yet planets such as Saturn and Uranus are much bigger. Jupiter, however, is larger than all the other planets in our solar system combined into one planet - now that is big. Compare Jupiter to our sun and Jupiter looks like a pea next to
football, put another way - the sun is huge and massive! Still, our sun, which we rely on so intimately, is one of a hundred billion stars in our massive galaxy "the milky way". The Milky Way is a hundred thousand light years across - meaning that it takes light 100.000
years to reach us from the other end of the galaxy (yet the light can whizz around the earth 7 times in one second). Our sun, which is huge, is not even close to one light year across - rather it is about one light minute...

Our huge Milky Way galaxy containing a hundred billion stars and with a diameter of about 100.000 light years is small compared to the local cluster of galaxies (a small cluster of half a dusin galaxies), which measured millions of light years across.

I think you see where this is going... Our local cluster, which is absolutely humungous, is tiny compared to the observable universe. The most distant galaxies that can be seen are about 14 billion (that's 14.000.000.000) light years away - suggesting that the observable universe has a diameter of maybe 28 billion light years. Our local cluster of galaxies is tiny in comparison...

Still, theory suggests that our 28 billion light year observable universe is just a small fraction of the true size of the universe (we cannot see the whole universe because galaxies far away may be travelling away from us faster than the speed of light in which case their light will never reach us). Maybe the observable universe is just "one billionth" of the size of our true universe.

At last - many theorists believe that our universe, in which we are much smaller than a grain of sand in the Sahara dessert, is but one out of a large number of universes...

I don't know about you, but these numbers make my heart beat faster. I feel small and improbable, but also grand, lucky and inspired - it turns all my daily woes into experiences - I feel lucky for having experienced what it feels like to be sad, angry or happy - I feel
lucky for being able to study all the grand aspects of nature - from our huge universe to our fantastic brains.