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Jupiter as depicted in Danny Phantom

Jupiter is the largest planet in the Solar System and the fifth planet from the Sun. Jupiter is a gas giant, both because it is so large and made up of mostly hydrogen. The other gas giants are Saturn, Uranus, Neptune, and the hypothetical Planet Nine (though Uranus, Neptune, and Planet Nine are sometimes classified as ice giants). Jupiter orbits 1,426,000,000 km away from the Sun. The planet is named after Jupiter, the supreme god of the Romans, also called Zeus by the Greeks. His sacred animal is the eagle and his wife is Hera or Juno; the latter's namesake is the asteroid 3 Juno.

Jupiter was estimated to be 700,000 km across when it was born; it is shrinking at 0.5 centimeters every year. The planet has a radius of 69,911 kilometers; 1,300 Earths could fit inside of it. It is also famous for its Great Red Spot, which is a giant spinning storm that is 1,5 times the width of the Earth and has been raging for over 350 years. On 7 July 1992, the comet Shoemaker-Levy 9 broke into several pieces; all of which crashed into Jupiter. Jupiter has a faint ring system.


Jupiter shown with six of its notable moons - Io, Europa, Ganymede, Callisto, Amalthea, and Thebe.

Jupiter was originally known to have 67 moons, but 12 more were discovered in July 2018, raising the total to 79.[1] The four largest are called the Galilean Moons because they were discovered by Galileo before all of the other ones:

The Galilean Moons
Name Diameter Features Image
Io 3,820 km Covered with volcanoes and sulfur.
Io highest resolution true color.jpg
Europa 3,122 km Its surface is cracked water ice. It could have an ocean below its icy surface.
Ganymede 5,262 km The largest moon in the Solar System, even larger than the planet Mercury.
Ganymede, moon of Jupiter, NASA.jpg
Callisto 4,820 km Has the oldest surface in the Solar System (4 billion years old) that remains unchanged
Callisto (Jovian Moon).jpg
Other notable moons
Amalthea ~170 km Red surface due to sulfur compounds from Io.
Thebe 98 km Consists of porous solid water with unknown amounts of other materials.
Callirrhoe 8.6 km[2] unknown

All of them are named after the lovers of Zeus (whose Roman equivalent is Jupiter).

Jupiter orbits the Sun at a distance of  million kilometers. NASA’s Juno spacecraft was launched in . On July 4, 2016, Juno arrived at Jupiter and is currently orbiting it. Juno is taking pictures of Jupiter’s north and south poles.

Sun-Jupiter barycenter

Jupiter is a binary companion to the Sun. The Sun and other planets orbit the Solar System barycenter, but the planets are too small and thus their gravitational pulls fail to bring the barycenter out of the Sun. But Jupiter is so large, its gravitational pull tugs the barycenter outside of the Sun.


By now, you should have a good understanding of the planet Jupiter. See if you can get all correct on the following test:

1 The Great Red Spot is:

an electric storm
a solar eclipse
Two other answers are correct (making this the only true answer).
the shadow of a moon
a magnetic storm

2 Which of the following statements is FALSE?

Jupiter has four large moons and many smaller ones
The Great Red Spot is a storm that has raged for over 300 years
Jupiter emits more energy than it receives from the Sun
Jupiter is the largest known planet
Jupiter has a system of rings

3 What is the mechanism that heats the interior of Jupiter?


4 Why is Jupiter an oblate spheroid?

tides from other gas planets
tides from the Sun
tides from the Jupiter's moons
rotation about axis
revolution around Sun

5 What statement best describes the Wikipedia's explanation of the helium (He) content of Jupiter's upper atmosphere (relative to the hydrogen (H) content)?

Jupiter's atmosphere has only 80% as much helium because the Helium fell to the core.
Jupiter's atmosphere has 80% more He because Jupiter's hydrogen escaped into space.
Jupiter's atmosphere has only 80% as much helium because the He escaped into space.
Jupiter's atmosphere has 80% more He because Jupiter's hydrogen fell to the core.
Jupiter and the Sun have nearly the same ratio of He to H.

6 Where is the Sun-Jupiter barycenter?

Just above the Sun's surface
Just above Jupiter's surface
At the center of the Sun
At the center of Jupiter
The question remains unresolved

7 The barycenter of two otherwise isolated celestial bodies is?

a place where two bodies exert equal and opposite gravitational forces
the focal point of two elliptical orbital paths
both of these are true

8 Knowing the barycenter of two stars is useful because it tells us the total mass


9 Knowing the barycenter of two stars is useful because it tells us the ratio of the two masses


10 Although there is some doubt as to who discovered Jupiter's great red spot, it is generally credited to

Tycho in
Galileo in 1605
Newton in 1668
Cassini in 1665
Messier in 1771

11 The bands in the atmosphere of Jupiter are associated with a patter of alternating wind velocities that are

easterly and westerly
updrafts and downdrafts
both of these

12 As one descends down to Jupiter's core, the temperature

stays about the same