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

CNN: A transit of Venus, an age of wondrous science

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.

BBC: Spiritual cleansing at Mela Bathers at Mela

"It happened probably right at the end of the formation of the four terrestrial planets - Mercury, Venus, Earth and Mars, " said Craig Agnor, a co-author on the Francis Nimmo study.

BBC: Mars' two-faced riddle 'solved'

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

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

Several panel members have favored dividing planets into categories: terrestrial planets (Mercury, Venus, Earth, Mars), giant planets (Jupiter, Saturn, Uranus, Neptune) and a third class that would include Pluto.

NPR: Dwarf Planets May Finally Get Respect