Although Mercury and the Moon never progressed beyond the planetary-congealing stage, volcanic activity on Mars, Venus and Earth created powerful forces that caused further mineral diversification.

ECONOMIST: Minerals

These upheavals will, supposedly, be the result of a planetary alignment, as the combined gravitational influences of the moon, Mercury, Venus, Mars, Jupiter and Saturn wreak havoc on the earth.

ECONOMIST: Not the end of the world

That means only Mercury and Venus (and our moon) can cause eclipses from a vantage point on the Earth.

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The Mauni Amavasya is a day when sun, moon, Venus and Mercury are in the zodiac of Capricorn, a rare but perfect alignment of planets, devotees believe.

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They have measured microwaves as they warped around the sun, studied variations in the orbit of Mercury, and bounced signals off the Moon and Mars.

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Scientists think mercury atoms may "hop" across the surface of the Moon towards the poles, causing them to be concentrated in these regions.

BBC: Nasa reveals new information about moon probes crash sites

And water would be all the more exciting on Ganymede because it is the largest moon in the solar system (larger even than the planets Mercury and Pluto) and, like earth, it has a permanent magnetic field that protects part of its surface from bombardment by certain sorts of life-destroying radiation.

ECONOMIST: Blue moon