April 4, 2013
from ExtremeTech Website
as seen by NASA's infrared Spitzer telescope
[The image is an infrared one of the core of the Milky Way,
captured by NASA's Spitzer space telescope.
Infrared imaging allows you to see many stars
which are normally
obscured by intergalactic dust.]
There are roughly 500 billion galaxies
in the universe, meaning there is somewhere in the region of
50,000,000,000,000,000,000,000 (5◊1022) habitable
planets. Iíll leave you to do the math on whether one of those 50
sextillion planets has the right conditions for nurturing alien life
Kepler essentially measures the dimming (apparent magnitude) of stars as planets transit in front of them - the more a star dims, the larger the planet.
Through repeated observations we can
work out the planetís orbital period, from which we can usually
derive the orbital distance and surface temperature. According to
Phil Yock from the University of Auckland, Keplerís technique
generally finds "Earth-sized planets that are quite close to parent
stars," and are therefore "generally hotter than Earth [and not
This results in a list of planets that are generally cooler than Earth - but by interpolating between this new list, and Keplerís list, the Kiwi astronomers hope to generate a more accurate list of habitable, Earth-like planets.
Essentially, light emitted by a star is bent by the gravity of massive objects, ultimately allowing astronomers to work out just how large those objects are.
Gravitational microlensing has been used in recent years to detect planets the size of Neptune or Jupiter, and now Yock his colleagues at the University of Auckland have proposed a new method for detecting Earth-sized planets.
The astronomers hope to use this new
microlensing technique with a huge suite of telescopes - located in
Chile, South Africa, Australia, New Zealand, Hawaii, and Texas - to
confirm their estimate of 100 billion Earth-like habitable planets.
The nearest probably-habitable planet is Tau Ceti e, which is 11.9 light years from Earth. The fastest spacecraft ever, Helios II, traveled at 43 miles per second (70km/s), or 0.000234c (the speed of light).
At that speed it would
take 51,000 years for a spacecraft to reach Tau Ceti e.
To reach another star within a reasonable time period (say, 50-100 years) we would need a propulsion system thatís capable of around 0.1c (10% light speed). There are a few proposed methods for reaching such insane speeds (antimatter rockets, fusion rockets), but nothing thatís being immediately (and seriously) considered for interstellar travel.
Who knows, maybe NASAís warp drive will
pan out? If they can work out the whole
annihilating-the-star-system-upon-arrival issue, that isÖ