Facts about the largest planet of our solar system (Jupiter)
Facts about the largest planet of our solar system (Jupiter)

                                    The biggest planet in our solar system

Jupiter is one of the brightest planets in our skies and the largest and most massive planet in the Solar System. It has faint rings, numerous moons, and an unstable surface. Jupiter is considered the giant or the Jovian planet, together with Saturn, Uranus, and Neptune. When ancient astronomers named Jupiter after the Roman ruler of all gods, they had no idea about its enormous size surpassing other planets. Yet, they came up with a very fitting name.

Jupiter's size

With a radius of 69,911 km, Jupiter is the biggest planet in the Solar System. In comparison, the second-biggest Saturn has a radius of 58,232 km (36,184 mi). Jupiter is also the most massive planet — it’s more than twice as massive as all the other planets combined

Jupiter's orbit and rotation

Each planet takes a certain amount of time to complete one orbit around the Sun and one rotation around its axis. As we live on the Earth, we take the local days (24 hours) and years (365.25 days) as a standard. Let's see how different from our planet Jupiter is.

Despite being the largest planet, Jupiter is also the fastest spinning planet in the Solar System; therefore, it has the shortest days. One day on Jupiter takes slightly less than 10 hours — the exact time varies from 9 hours and 56 minutes around the poles to 9 hours and 50 minutes close to the equator. The reason behind this difference is that Jupiter is a gas planet and doesn’t rotate as a solid sphere. Instead, its equator rotates slightly faster than the polar regions, which leads to the distinction in the day length in different areas.

One Jovian year takes 11.8618 Earth years or 4,332.59 Earth days. In comparison, the second-largest planet Saturn has an orbital period of around 29 Earth years and the smallest Mercury revolves around the Sun every 88 Earth days

How many Earths can fit in Jupiter?

It would take more than 1,300 Earths to build a single Jupiter. If the gas giant were the size of a basketball, the Earth would be the size of a grape.

How far is Jupiter from the Sun?

The gas giant is 5.2 AU from the Sun or 778 million km away. In comparison, Mercury, the closest planet to the Sun, is 0.4 AU or roughly 58 million km away from our star. (One astronomical unit (AU) is the distance between the Sun and the Earth.)

How far is Jupiter from the Earth?

The distance between planets is constantly changing because they are moving along their orbits. Jupiter is only 588 million km away when it’s closest to our planet and 968 million km at its farthest.

How long does it take to get to Jupiter?

For a simple flyby, it will take about 550-650 days as it happened with the Voyager spacecraft: Voyager 1 took only 546 days, and Voyager 2 took 688 days. However, if you’re planning to go into Jupiter’s orbit, you’ll need to be going slowly enough when you reach the planet. For example, NASA’s Galileo spacecraft flight duration was 2,242 days before it finally arrived at Jupiter.

What is Jupiter made of?

Jupiter doesn’t have a solid surface; its atmosphere just gets denser the farther down you go, transitioning into a liquid layer surrounding a small core. Simply, it means that the atmosphere of Jupiter makes up almost the entire planet. Jupiter (and its atmosphere) consists of about 90 % hydrogen and 10 % helium — which is very similar to the Sun’s composition.

Jupiter’s formation

Like other planets in the Solar System, Jupiter formed about 4.5 billion years ago, when gravity pulled gas and dust together to create the gas giant. The planet took most of the mass left over after the formation of the Sun and became more than twice the combined material of the other bodies in the Solar System. About 4 billion years ago, Jupiter settled into its current position as the fifth planet from the Sun.

Jupiter's structure

We still don’t know for sure what Jupiter’s core looks like. It might consist of solid materials or be a thick, boiling, dense soup. What we know is that the core is surrounded by a layer of liquid metallic hydrogen that extends out to 90% of the planet’s diameter.

Jupiter's surface

This gas giant doesn’t have the hard surface as we do on the Earth. The planet is mostly swirling gases and liquids. A spacecraft can’t land on it or fly through the planet due to the extreme pressures and temperatures that will crush, melt, and vaporize it.

What is the Great Red spot on Jupiter?

The Great Red Spot is a giant storm about twice as wide as the Earth located in Jupiter’s Southern Hemisphere. It consists of crimson-coloured clouds that spin counter-clockwise at a speed that exceeds any storm’s speed on the Earth.

This storm was first observed in 1878; however, Gian Domenico Cassini in 1665 mentioned “Permanent Storm,” which is believed to be the Great Red Spot. Such a long-lasting storm can be explained by the absence of a solid surface on Jupiter. On the Earth, hurricanes disintegrate when they reach solid ground, but the Red Spot simply doesn’t have land to collide with.

However, the Great Red Spot has been shrinking over the years: from a length of about 40,000 km (24,850 mi) in 1879 to nearly 15,000 km (9,320 mi) in 2021. The reasons behind it are unknown.

Jupiter's moons

Jupiter and its numerous satellites resemble a miniature Solar System and present a scientific interest for astronomers around the world.

How many moons does Jupiter have?

Jupiter has 79 moons: 53 of them are named, and 26 are waiting for an official name. Most of them are small — about 60 satellites are less than 10 km (6.2 mi) in diameter. The number of moons is constantly changing; in 2003, astronomers discovered 23 new moons, then, in 2018, 12 more Jovian moons were found. As of 2021, Jupiter is losing to Saturn on the number of satellites; according to NASA, the ringed planet has 82 moons.

What is Jupiter's 4 largest moons?

Jupiter’s four largest moons are Io, Europa, Ganymede, and Calisto. They’re called the Galilean satellites after their discoverer and are as remarkable as Jupiter itself.

The largest one, Ganymede, is bigger than Mercury and is known as the most gigantic satellite in the Solar System. It even has its own magnetic field! Europa, in its turn, has a very high potential to be habitable — there is evidence of a vast ocean just beneath its icy surface. It’s thought to have twice as much water as the Earth. Io is the most volcanically active body in the Solar System, with hundreds of volcanoes on it.

Calisto, which is about the same size as Mercury (99% of its diameter, to be precise), is the third-largest satellite in our Solar System and may look boring against the background of the other three moons. However, in the 1990s, NASA’s Galileo spacecraft revealed that there might be a salty ocean beneath Calisto’s surface.

Jupiter's rings

The Jovian ring system was the third ring system discovered in the Solar System, after those of Saturn and Uranus. Jupiter’s rings are faint and mostly consist of dust; they’re likely leftovers from meteor bombardment of Jovian moons.

How many rings does Jupiter have?

Jupiter has four rings: the closest to the planet faint halo ring, a relatively bright but very thin main ring, and two wide and thick gossamer rings — the Amalthea and the Thebe. The last two are named after the moons of whose material they consist of.

Are Jupiter's rings visible?

We surely won’t see the Jupiter rings with the naked eye since they’re too faint and tenuous. For ground-based observation, the largest telescopes available are required. Even from space, they’re visible only when viewed from behind Jupiter and are lit by the Sun or directly viewed in the infrared.

Missions to Jupiter

Since 1973, nine spacecraft have visited Jupiter. The most noteworthy ones are:

  1. The first one was NASA’s Pioneer 10 that provided hundreds of Jupiter’s photos and collected some measurements. The Pioneer 11 in 1974 got three times closer to the planet than its predecessor.
  2. In 1979, the famous Voyager spacecraft discovered the Jovian ring system and took thousands of pictures of clouds and storms on the planet. Those pictures also showed that the mysterious Great Red Spot is a gigantic storm. Moreover, Voyager 1 and 2 discovered dozens of volcanoes on Jupiter’s moon Io — the first found active volcanoes on another space object.
  3. NASA’s Galileo probe became the first spacecraft to enter Jupiter’s orbit; it arrived on the planet in 1995. The Galileo mission, among many other things, examined Jupiter’s atmosphere and immense magnetic field and closely studied the Galilean moons. Several years later, in 2000, the Cassini spacecraft that was heading to Saturn took some of the best photos we have of Jupiter.
  4. The second spacecraft ever to enter Jupiter’s orbit is called Juno. It arrived at Jupiter in 2016 and will be exploring the gas giant until September 2025 or the spacecraft's end of life.


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