Space Topics

Section Highlights

Space Missions

News and facts about the spacecraft that have explored the planets beyond Earth.

Compare the Planets

Comparing the physical characteristics of the planets and other things in our solar system (and beyond)

All asteroids and comets ever visited by spacecraft, to scale, with text (thumbnail)

Space Imaging

Most deep-space missions carry cameras to acquire scientific data; but these data can also be used to produce stunning views of distant worlds. And almost all of this data is free and readily available to the public for download.

Citizen Science

Citizen Science projects harness the efforts of thousands of space enthusiasts to amass data sets that no single scientist could ever produce.

Our Sun

The Sun is a variable star with an 11-year cycle of storm and quiet activity.

Mercury

Planet Mercury orbits closest to the Sun, and has had only two visitors: MESSENGER and Mariner 10.

Venus

It's our nearest neighbor and a near twin to Earth in size and composition. But, compared to the rest of the terrestrial worlds, we know little about Venus.

Our Moon

The Moon, destination of the Apollo program, now the proving ground for a new generation of space-faring nations.

Mars

Science of Mars and its exploration by orbiters and rovers Curiosity and Opportunity

Asteroids and Comets

Asteroids in the main belt or near Earth; comets in the Kuiper belt or visiting the Sun; near-Earth objects and the impact hazard they represent

Outer Planets

Outer Planets Jupiter, Saturn, Uranus, and Neptune have retinues of moons and rings that make them like mini-solar systems.

Pluto's Neighborhood

Pluto's Neighborhood: Kuiper Belt, Dwarf Planets, Centaurs, and Sedna

Extrasolar Planets

Extrasolar planets being discovered by Kepler and the world's great telescopes

Life in the Universe

Could humans be the only intelligent beings in all the vastness of the universe? Or are we just one humble race, a member of a vast intergalactic fraternity of advanced civilizations? Is there other life in the solar system, or are we alone?