Average temperature of the Moon during the day: 224 F

Average temperature of the Moon at night: -243 F

Weight of a single teaspoon of a neutron star: 6 billion tons

Number of Earths that could fit inside the sun: 1 million

Number of years required to fly to Pluto in an airliner: 800

Length of a day on Jupiter: 10 hours

Length of a day on Neptune: 16 hours

Speed required for a rocket to get into orbit: 17,600 mph

The longest time an astronaut has spent in space: 341 days

Length of one day on Mercury: 59 Earth days

The only planet that spins clockwise: Venus

The densest planet in the solar system: Earth

First living creatures sent into space: fruit flies

Color of the sunsets on Mars: blue


Europa, one of Jupiter’s moons, has saltwater geysers that are 20 times taller than Mt. Everest.

Since it was discovered in 1846, Neptune has made only a single orbit of the Sun, completing the circuit in 2011. It takes Neptune 165 years to orbit the Sun once.

Uranus was named for the Greek god of the sky who, according to Greek mythology, was the great-grandfather of Ares (Mars), grandfather of Zeus (Jupiter) and father of Cronus (Saturn).


Neptune’s moon Triton is the coldest known object in the solar system with an average surface temperature of -391° F.

Ganymede, a moon that orbits Jupiter, is the largest moon in the Solar System, and is even bigger than the planet, Mercury. Ganymede would be classified as a planet if it orbited the Sun directly. The icy-rock surface has both craters and grooves, and a molten core, which allows it to possess its own magnetosphere within that of Jupiter.

In 1996, the Hubble Telescope detected a thin atmosphere surrounding Ganymede, which contained oxygen. However, it’s far too thin to support life.

Dactyl is a moon less than a mile in diameter which orbits the asteroid Ida. It was discovered by the Galileo probe in 1995, in the Koronis asteroid belt between Mars and Jupiter. Before this, scientists had not known that asteroids could have moons, but since its discovery a further 24 have been found which have moons orbiting around them.

“Gliese 436 b” is a Neptune-sized exoplanet located approximately 30 light-years from Earth. Immense gravitational forces have compressed the planet’s water into Ice-X, and even though the planet is around 1,000 F, Ice-X does not melt.

What does space smell like? Here are a few descriptions by astronauts: “Seared steak.” “Hot metal.” “Welding fumes.” “Carries a distinct odor of ozone, a faint acrid smell.” “Sulfurous.” “Just imagine sweaty feet and stale body odor, mix that odor with nail polish remover and gasoline … then you get close!”

The largest moon is Jupiter’s Ganymede, and the smallest is Mar’s Deimos. Ganymede has a diameter of 3,273 miles (5,267 km), and Deimos has a diameter of 7 miles (11 km).