The biggest comet this year will be ISON in late November.

The biggest comet this year will be ISON in late November.

Saturn’s density is less than that of water.
Charon, Pluto’s largest moon, has nearly half the radius of Pluto.

Charon, Pluto’s largest moon, has nearly half the radius of Pluto.

The Moon orbits the Earth once for every time it rotates on its axis.

The Moon orbits the Earth once for every time it rotates on its axis.

The closest planet to the Sun actually gets pretty cold.

The closest planet to the Sun actually gets pretty cold.

The Sun is 400 times larger than the Moon but is 400 times farther away from Earth, making them appear the same size.

The Sun is 400 times larger than the Moon but is 400 times farther away from Earth, making them appear the same size.

Today is the 35th anniversary of the launch of Voyager 1.

Today is the 35th anniversary of the launch of Voyager 1.

The mass of Mars in Mars Bars. 

The mass of Mars in Mars Bars. 

The number of stars in the observable universe is also about equal to the number of atoms in 6 grams of carbon-12. 

The number of stars in the observable universe is also about equal to the number of atoms in 6 grams of carbon-12. 

Avogadro’s number is about twice the number of stars in the observable universe.

Avogadro’s number is about twice the number of stars in the observable universe.