NASA Spies Earth-Sized Exoplanet Orbiting Sun-Like Star

An anonymous reader writes: NASA has announced that a new Earth-like planet has been discovered that may be the closest thing yet to a first true "Earth twin." Kepler 452b is located 1,000 light years away, is 60% larger than Earth, and orbits Kepler 452 at a distance similar to that between Earth and the Sun. "It is the first terrestrial planet in the habitable zone around a star very similar to the Sun," says Douglas Caldwell, an astronomer at the SETI Institute in Mountain View, California.

Comments

2 time the gravity thought

[Eloking]

2 time the gravity thought...

Re:2 time the gravity thought

[CrimsonAvenger]

You did, in fact, "forget how to science" - he's right.

From TFA, it's 1.6x the diameter of Earth, and 5x the mass of Earth.

Which puts it about 2x the surface G, when rounded to two significant digits (1.95+).

Note this world is rather denser than Earth - 5x the mass packed into 4x the volume. Should be a great place for heavy metal poisoning. Or toxic wastelands. Something like that....

Re:2 time the gravity thought

[MightyMartian]

I'm thinking the worst aspect of that higher gravity would be a much denser atmosphere. We certainly could survive in 1.6g environment, but we couldn't survive the crushing weight of that atmosphere.

Re:2 time the gravity thought

[CrimsonAvenger]

And I repeat: from TFA, mass of the planet is 5x Earth Mass. Diameter (and radius) is 1.6x Earth.

Insert 5x mass and 1.6x radius into Gm/r^2, and you very quickly realize that:

1) density isn't the same as Earth's. It is, in fact, a.25x Earth density.

2) surface gravity will be ~2x Earth (1.95+g).

Re:2 time the gravity thought

[ChrisK87]

"Note this world is rather denser than Earth - 5x the mass packed into 4x the volume. Should be a great place for heavy metal poisoning. Or toxic wastelands. Something like that...."

Not necessarily. A planet with a larger radius retains heat better thanks to its lower surface area to volume ratio, and a planet with higher gravity will more efficiently separate its component materials by density, i.e. drawing metal elements into its core. And since the planet is retaining more heat, it will probably have had more resurfacing and tectonic activity than Earth did. So a denser planet does have more metals, but by being larger it is also going to have a lower proportion of it [metals present during formation] in its crust than a 1G planet.

As to which effect dominates in this situation, that's a question for someone with an actual model of planetary evolution.

Re:2 time the gravity thought

[mark-t]

from TFA, mass of the planet is 5x Earth Mass.

I'm not sure what you were reading.... From the page linked to the summary:

Scientists do not know if Kepler-452b can support life or not. What is known about the planet is that it is about 60 percent larger than Earth, placing it in a class of planets dubbed "super-Earths." While its mass and composition are not yet determined, previous research suggests that planets the size of Kepler-452b have a better than even chance of being rocky.

So I'm not sure where you got 5 times the mass from.

In fact, if we assume composition similar to earth, a planet 1.6 times the size of earth would have 4.096 (1.6 cubed) times the mass of earth

Because gravitational pull falls with the square of the distance, we could divide 1.6 cubed times the mass of earth by the square of 1.6 gives us exactly 1.6 times earth's gravitational pull at the surface of the planet. Thus, assuming identical composition, surface gravity scales linearly with diameter. While it probably doesn't have absolutely identical composition to Earth, there is not yet any compelling reason at this time to speculate that its composition would be drastically different either. Certainly if its density were 25% heavier than that of earth, then the mass (and surface gravity) would be exactly as you described. According to the page, we do not know that information yet, however.

Re:2 time the gravity thought

[Last_Available_Usern]

Maybe this is where Eddie Lacy is from.

Too Far Away

[lazarus]

It is 1400 light years away. It may be a good candidate for life, but we will never know. Even if we point SETI-type radio telescopes at it and monitor it for signals, they will have spent 1400 years getting to us and there is no guarantee that whatever civilization was there is still there. Chances of a "conversation" are nil.

If we detect life-emitting organic compounds on it, it also won't matter. We'd never be able to verify their veracity because we cannot get there.

Interesting discovery, but I can't muster up much excitement about this one.