Planet Basics
Name the planet closest to the Sun.
Mercury
Are the inner planets mostly solid or gas?
The four inner planets are solid, rocky planets (Mercury, Venus, Earth, and Mars).
What is a comet made of?
Comets are essentially "dirty snowballs", composed primarily of ice, dust, and rock.
What force keeps planets in orbit?
The force of gravity is the primary force that keeps planets in orbit around a star, like the Sun. This force pulls objects with mass towards each other, and in the case of the solar system, the Sun's immense gravitational pull is what prevents the planets from flying off into space.
Which planet has a day longer than its year?
The planet with a day longer than its year is Venus. It takes Venus 243 Earth days to rotate once on its axis (a Venusian day), but only 225 Earth days to complete one orbit of the Sun (a Venusian year).
Which planet is known as the red Planet?
Mars
Which outer planet has the most visible rings?
Saturn has the most visible rings.
What is the asteroid belt and where is it?
The asteroid belt is a region in our solar system located between the orbits of Mars and Jupiter.
What shape are planetary orbits?
Planetary orbits in our solar system are elliptical, not perfect circles.
What planet spins on its side?
Uranus is the planet that spins virtually on its side, with its axis of rotation tilted at a remarkable 97.77 degrees.
Which planet has the most moons?
Saturn has 274 confirmed moons.
Name all the terrestrial planets.
Mercury, Venus, Earth, and Mars.
What’s the difference between meteoroids, meteors, and meteorites?
A meteoroid is a small rocky or metallic object traveling through space. A meteor is a meteoroid that has entered Earth's atmosphere and is burning up, creating a bright streak of light. A meteorite is a meteoroid that has survived the atmospheric passage and landed on Earth.
Why does the Moon orbit Earth instead of the Sun?
The Moon orbits Earth, rather than the Sun, primarily due to the influence of distance and gravity. While the Sun's gravitational pull on the Moon is stronger than Earth's, the Moon is much closer to Earth than to the Sun.
How many Earths could fit inside Jupiter?
Approximately 1321 Earths could fit inside Jupiter. Jupiter's volume is significantly larger than Earth's, and this calculation is based on the ratio of their volumes.
Why is Venus hotter than Mercury?
Venus has a thick, dense atmosphere that traps heat.
Compare atmosphere of gas giants vs. inner planets.
Gas giants (Jupiter, Saturn, Uranus, Neptune) have atmosphere dominated by hydrogen and helium, while inner planets (Mercury, Venus, Earth, Mars) have atmospheres composed primarily of nitrogen, oxygen, and carbon dioxide.
What defines a “dwarf planet”?
A celestial body that orbits the Sun, has enough mass to be nearly spherical due to its own gravity, but has not cleared its neighborhood of other objects of comparable size.
What causes the tides on Earth?
Tides, the periodic rise and fall of sea levels, are primarily caused by the gravitational forces of the Moon and the Sun acting on the Earth's oceans. The Moon's gravitational pull creates a bulge of water on the side of Earth closest to the Moon, while inertia causes a similar bulge on the opposite side.
What is the Kuiper Belt?
The Kuiper Belt is a region in our solar system located beyond Neptune, filled with icy bodies like dwarf planets and comets.
Which planet has the fastest winds?
Neptune
Which planet has the strongest magnetic field and why?
Jupiter possesses the strongest magnetic field in our solar system. It is generated by the rapid rotation and circulation of liquid metallic hydrogen within its core.
Name one moon scientists believe might have liquid oceans.
One moon that scientists believe might have a liquid ocean is Europa, Jupiter's fourth largest moon. Evidence suggests a salty ocean lies beneath its icy surface.
Why don’t the planets float away from the Sun?
Planets don't float away from the Sun because of a perfect balance between the Sun's gravity and the planets' own forward motion. The Sun's immense gravity pulls the planets towards it, but the planets are also moving very quickly, which causes them to "fall" around the Sun in curved paths called orbits. This continuous "falling" and "missing" is what keeps them in their orbits.
What is the Oort Cloud and what does it contain?
The Oort cloud is a theoretical shell of icy objects, primarily comets, that is thought to surround our solar system at a great distance, beyond the Kuiper Belt and even beyond the Sun's gravitational influence.