Scientists Discover Exoplanet Less Than Twice the Mass of Earth 201
Snowblindeye writes with this excerpt from the European Southern Observatory:
"Well-known exoplanet researcher Michel Mayor today announced the discovery of the lightest exoplanet found so far. The planet, 'e,' in the famous system Gliese 581, is only about twice the mass of Earth. The team also refined the orbit of the planet Gliese 581 d, first discovered in 2007, placing it well within the habitable zone, where liquid water oceans could exist. Planet Gliese 581 e orbits its host star — located only 20.5 light-years away in the constellation Libra ('the Scales') — in just 3.15 days. 'With only 1.9 Earth-masses, it is the least massive exoplanet ever detected and is, very likely, a rocky planet,' says co-author Xavier Bonfils from Grenoble Observatory. Being so close to its host star, the planet is not in the habitable zone. But another planet in this system appears to be. ... The planet furthest out, Gliese 581 d, orbits its host star in 66.8 days. 'Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star,' says team member Stephane Udry. The new observations have revealed that this planet is in the habitable zone, where liquid water could exist. '"d" could even be covered by a large and deep ocean — it is the first serious "water world" candidate,' continued Udry."
Wanna see more: Celestia (Score:5, Informative)
Just select "go to object" and type in "gliese 581", you'll get the orbits of the different planets already found too.
The neat thing is, you can just "cruise" around, speed up time to see how stellar objects move, and so on... Quite cool
Re:Let's blow this popsicle stand (Score:2, Informative)
Yeah, if we were able to travel at the speed of light.
Re:but what about Earth 2... (Score:3, Informative)
Re:Did any one else read that as... (Score:4, Informative)
Re:but what about Earth 2... (Score:3, Informative)
> This is very interesting but no where near as exciting as finding another Earth like planet.
Planet Gliese 581 e is an earth-like planet. It's just not in an earth-like orbit.
We get it already! (Score:1, Informative)
Re:Planets and moons (Score:5, Informative)
One interesting thing about Gliese 581 d not being made of rock is that it might have almost the same surface gravity as Earth:
Volume of a sphere=(4/3)*pi*radius^3
radius of sphere=((.75/pi)*volume)^(1/3)
volume=mass/density
radius=((.75/pi)*mass/density)^(1/3)
mass=7.5*mass of earth
density=2kg/liter (twice that of water)
acceleration due to gravity=Gravitational constant*Mass of planet/(radius)^2
thus, plug this into google=
(Gravitational constant)*(7.5*mass of the earth)/((7.5*mass of the earth)/(2kg/liter)*.75/pi)^(2/3)
google gives us: 9.7764354 m / s^2
Yay!
Now, we just need a breathable atmosphere! And light-speed spaceships (or faster)!
Better hurry! (Score:1, Informative)
You do realise that the universe has an awkward tendency to expand, right?
So it's 20.5 lightyears away *now*...
We better get going quickly!
*packing bags*
Re:Astronomy (Score:5, Informative)
The significance is that our methodology is improving. Only in the past decade or so have we been able to identify stars with possible planets. Only in the past year or two have we been able to directly image a planet (or separate it's image from the parent star). What we know of the planets is based on how close it's orbit is to the star, it's estimated mass, and in a few recent cases, based on limited spectroscopic information.
Now that Kepler's working, over the next 2-3 years we should have a flood of these reports. (keep in mind Kepler's only imaging a 10 x 10 degree patch of sky) In the next decade we will develop the means to directly image a nearby terrestrial sized planet.
All of the planets imaged so far are relatively close, on a galactic scale. A few 10's of light years. There's more than enough information out there to explain how far that is from a human perspective. Let's just say, that based on current technology, none of our great-grand children will get an up close look. (although I suppose we could do a fly by of something like the Gliese 581 system, with a probe, in the next 3-4 generations, if we tried hard enough.
Re:Strange biology (Score:4, Informative)
Re:Did any one else read that as... (Score:4, Informative)
Re:Let's blow this popsicle stand (Score:1, Informative)
No it shouldn't read that way. A light-year is a valid unit of measurement, which is derived from the distance one travels in a year at the speed of light. But that doesn't make "light-year" an invalid derived measurement.
Re:but what about Earth 2... (Score:3, Informative)
To elaborate on that (you covered the distance part, yourself), the main factors is detecting exoplanets right now are (1) its easier to detect bigger exoplanets, and (2) its easier to detect exoplanets closer to the stars they orbit. So, gas giants orbitting close to the stars are comparatively easy to detect, anything smaller and/or more distant is harder.
You can't generalize well from the results of a highly-biased detection system.
Re:'lighest'? (Score:3, Informative)
No. The correct term is lightest. The writers are not making any indication about density in the summary. They are indicating they they have indeed found the lightest planet discovered using these techniques. This planet wouldn't even be close to being the least dense planet ever discovered. Gas giants are typically far less dense.
(having to wait my obligatory five minutes between posts)
Re:Good news (Score:2, Informative)
Apologies to xkcd [xkcd.com]