Test your knowledge with these top questions!
Which gas makes up most of Jupiter's atmosphere?
Helium is the next most common gas, and deeper inside Jupiter the pressure squeezes hydrogen into a metal-like liquid that conducts electricity.
Which astronomer first observed Jupiter's four largest moons?
Galileo spotted them in 1610, and watching them circle Jupiter showed that not everything in the sky orbits Earth.
Where is Jupiter's Great Red Spot relative to the equator?
The Great Red Spot is a high-pressure storm, unlike Earth's hurricanes, which form around low pressure.
Which of Jupiter's four largest moons is the smallest?
Europa is a little smaller than Earth's Moon, making it the sixth-largest moon in the solar system.
Why does Uranus appear blue-green through telescopes?
Methane high in Uranus's atmosphere absorbs red wavelengths, leaving more blue and green light to reach observers.
Why does Jupiter bulge at its equator?
Jupiter rotates once in roughly 10 hours, and centrifugal effects push its equator outward.
Why are Uranus's rings difficult to see from Earth?
Dark particles and narrow bands make Uranus's rings much fainter than Saturn's bright rings.
What is Jupiter's Great Red Spot?
Jupiter's Great Red Spot is a long-lived anticyclonic storm in the planet's atmosphere.
How does Uranus rotate compared with most planets?
An axial tilt of about 98 degrees gives Uranus seasons that last roughly 21 Earth years.
Which mythological figure gives Uranus its name?
Most planet names come from Roman mythology; Uranus instead follows the Greek name Ouranos.