How Mercury and Venus can guide our hunt for alien life on exoplanets

New Scientist ^ | June 19, 2019 | Leah Crane

[EdnaMode]

Earth's nearest neighbours have turned into uninhabitable hellholes. Understanding their transformation will teach us which rocky exoplanets might be fit for life

CLOSE to the sun lie a pair of sizzling coals. You could be forgiven for thinking these strange worlds were two circles of hell: Mercury, a black and blasted plain, and Venus, a sweltering world beset by rain of pure acid.

But for all the terror of their outward appearance, their insides are remarkably familiar. Along with Earth and Mars, they form the solar system’s only rocky planets, a stark contrast to the bloated gas giants that make up its outermost worlds. In the language of those hunting for extraterrestrial life, such planets count as potentially habitable. In fact, if we found a Mercury or a Venus in a solar system far from our own, we might even call them Earth-like.

So what caused these seemingly Earth-like planets to become so resolutely, well, not? Was it some accident of composition, or millions of years spent in an inhospitable environment? Getting to the bottom of these questions, and understanding the diversity of rocky planets, is of paramount importance for astronomy. Without clear answers, we aren’t only ignorant of our own solar system’s history, but blinkered in our search for life elsewhere.

Part of the problem is that the innermost planets are incredibly hard to visit. Only two spacecraft have ever made it to Mercury and of the numerous Venus landers, none survived longer than 90 minutes.

[EdnaMode]

Mercury and Venus are uninhabitable hellholes? They must have elected Democrats.

[Fungi]

“Earth’s nearest neighbours have turned into uninhabitable hellholes.” Really? How do you know that and when were they not “uninhabitable hellholes?” Always start with a false premise and watch the liberals fall in line. Nonsense.

[faithhopecharity]

im not so sure mercury is an ‘uninhabitable hellhole’

maybe the author was thinking of Chicago (or SF or LA or Detroit or/?) instead?

[JohnBrowdie]

speaking of this ridiculousness, where is that UFO guy? seems like his handle started with a Q.

*not to be confused with the present day Q freaks, of course.

[who_would_fardels_bear]

Why are they hell holes?

1) Too small or too big
2) Too close or too far from sun
3) No magnetic field to protect an atmosphere from the solar wind and cosmic rays
4) No moon to provide tides
5) Improper tilt or rate of rotation
6) Unlucky history, e.g. hit by enormous asteroid or rogue planet
7) Insufficient amount of liquid water

[who_would_fardels_bear]

You mean QUIX!

[SunkenCiv]

Thanks EdnaMode.

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[SunkenCiv]

Thanks EdnaMode.

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[Windflier]

where is that UFO guy? seems like his handle started with a Q.

That would be Quix. He's no longer in residence here, but still lurks.

[SunkenCiv]

I miss Quix. Meanwhile...

[SunkenCiv]

I was sort of keeping in touch with him, but mea culpa, I'm not too great at that. [blush]

[SunkenCiv]

One night with Venus, a lifetime with Mercury.

[wally_bert]

The cosmic equivalent of them anyway.