Re-thinking an alien world

Forty light years from Earth, a rocky world named "55 Cancri e" circles perilously close to a stellar inferno.  Completing one orbit in only 18 hours, the alien planet is 26 times closer to its parent star than Mercury is to the Sun. If Earth were in the same position, the soil beneath our feet would heat up to about 3200 F.  Researchers have long thought that 55 Cancri e must be a wasteland of parched rock.

Now they’re thinking again.  New observations by NASA's Spitzer Space Telescope suggest that 55 Cancri e may be wetter and weirder than anyone imagined.

Spitzer recently measured the extraordinarily small amount of light 55 Cancri e blocks when it crosses in front of its star. These transits occur every 18 hours, giving researchers repeated opportunities to gather the data they need to estimate the width, volume and density of the planet.

According to the new observations, 55 Cancri e has a mass 7.8 times and a radius just over twice that of Earth. Those properties place 55 Cancri e in the "super-Earth" class of exoplanets, a few dozen of which have been found. Only a handful of known super-Earths, however, cross the face of their stars as viewed from our vantage point in the cosmos, so 55 Cancri e is better understood than most.

When 55 Cancri e was discovered in 2004, initial estimates of its size and mass were consistent with a dense planet of solid rock.  Spitzer data suggest otherwise: About a fifth of the planet's mass must be made of light elements and compounds--including water. Given the intense heat and high pressure these materials likely experience, researchers think the compounds likely exist in a "supercritical" fluid state.

A supercritical fluid is a high-pressure, high-temperature state of matter best described as a liquid-like gas, and a marvelous solvent. Water becomes supercritical in some steam turbines--and it tends to dissolve the tips of the turbine blades. Supercritical carbon dioxide is used to remove caffeine from coffee beans, and sometimes to dry-clean clothes. Liquid-fueled rocket propellant is also supercritical when it emerges from the tail of a spaceship.

On 55 Cancri e, this stuff may be literally oozing--or is it steaming?--out of the rocks.

With supercritical solvents rising from the planet’s surface, a star of terrifying proportions filling much of the daytime sky, and whole years rushing past in a matter of hours, 55 Cancri e teaches a valuable lesson: Just because a planet is similar in size to Earth does not mean the planet is like .

It’s something to re-think about.


Explore further

Stellar eclipse gives glimpse of exoplanet

Provided by Science@NASA
Citation: Re-thinking an alien world (2012, January 16) retrieved 24 May 2019 from https://phys.org/news/2012-01-re-thinking-alien-world.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
0 shares

Feedback to editors

User comments

Jan 16, 2012
Just because a planet is similar in size to Earth does not mean the planet is like Earth.

It's something to re-think about.

No sh*t, Sherlock. Ever looked at planets in our own solar system that are roughly in the same size category as Earth? Venus? Mars? Both VERY different.

If you need to "rethink" that then you haven't thought at all in the first place.

Jan 16, 2012
" On 55 Cancri e, this stuff may be literally oozing--or is it steaming?--out of the rocks. "

....All this time I thought it was called " effusion ".

Jan 16, 2012
If mars has 10% more mass than earth i dont call that the same size.

Anyway if u want concept of aliens and stuff Mass Effect is a good game.

350
Jan 16, 2012
If you want a "good" concept about alien life and planets, a game is the last place you should look...

Jan 16, 2012
"Supercritical fluid... For removing caffiene from coffee beans" Captain Janeway would never stop at this planet.

Xbw
Jan 16, 2012
If mars has 10% more mass than earth i dont call that the same size.

Anyway if u want concept of aliens and stuff Mass Effect is a good game.

Uhh what? Earth is much more massive than Mars. Over 9 times as massive in fact http://en.wikiped..._by_size

By massive, I mean actual mass of course. Not size.

Jan 16, 2012

Uhh what? Earth is much more massive than Mars. Over 9 times as massive in fact

My mistake i meant to say earth around ten times more massive than mars. But still i dont consider mars and earth around the same size, big difference.

If you want a "good" concept about alien life and planets, a game is the last place you should look...

I didnt mean factual concepts ofcourse since "alien life" is very fictional.

But i think they need to look at multiple factors not just size but also mass; the key is surface gravity.

350
Jan 16, 2012
The likelihood and possibility of alien life is far from fiction. Only a closed minded person would so readily dismis the likelihood and posibility of extra-terestrial life.

Jan 17, 2012
The likelihood and possibility of alien life is far from fiction. Only a closed minded person would so readily dismis the likelihood and posibility of extra-terestrial life.


I never said there is no possibility of E.T. life. I said the concept of how that looks like is completely fictional.

350
Jan 17, 2012
I see, you might clarify next time. I agree we can't have any reasonable idea about what any extra terestrial life might look like. We can only wait with anxious excitement about the limitless possibilities.

Jan 22, 2012
350.. You have to remember it is difficult to clarify anything when one is constantly reminded that "Brevity is the soul of wit". Everyone tends to take shortcuts in expressing themselves here.

And I have a question: Is "super earth" truly a definition used to describe other worlds? It seems so juvenile.

Jan 23, 2012
Is "super earth" truly a definition used to describe other worlds?

Yes. 'Super' just means 'over, above, more than'. It's a common latin prefix and you'll find it used in all kinds of scientific textbooks (from medical to chemistry and engineering) in all kinds of contexts.

Jan 23, 2012
Just because a planet is similar in size to Earth does not mean the planet is like Earth.

It's something to re-think about.

No sh*t, Sherlock. Ever looked at planets in our own solar system that are roughly in the same size category as Earth? Venus? Mars? Both VERY different.

If you need to "rethink" that then you haven't thought at all in the first place.


Exactly.

It's also not very accurate to call this planet a "super Earth", since it doesn't really resemble Earth at all.

Jan 23, 2012
The definition of 'super Earth' only applies to mass - nothing else. Anything with up to 10 times the mass of Earth is a 'super Earth'.

Extrasolar, sub-stellar, objects of significant mass fall into one or more of these categories:

Pulsar planet
Circumbinary planet
Super-Earth
Hot Neptune
Hot Jupiter
Eccentric Jupiter
Gas giant
Goldilocks planet
Terrestrial planet
Chthonian planet
Ocean planet
Carbon planet
Iron planet
Helium planet
Coreless planet
Interstellar planet
Planetary system
Extrasolar moon
Extragalactic planet

Source:
http://en.wikiped...ications

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more