How many planets are there? Mercury is the smallest planet, followed by Venus, Mars, and Earth. Neptune, Uranus, and Saturn are the next largest, but Jupiter is the largest planet in terms of mass. Mercury has the least mass of all the planets, and its size is the same as Earth’s. The two smallest planets, Sedna and Pluto, are also smaller than Earth.
In order to make the comparison between the smallest to the largest planet, let’s first discuss Mercury. Located in the constellation Cygnus, Mercury is the smallest planet in the solar system. The surface of Mercury looks similar to that of the moon, with mountains and craters that are reminiscent of the moon. Since Mercury lacks an atmosphere, its surface temperature varies more than that of other planets. Mercury’s equatorial regions are always below 180 K.
Mercury is smaller than Pluto, the smallest planet in our solar system. The equatorial diameter of Pluto is 2,302 kilometers, or about half of the size of Mercury. A 12-inch Mercury globe made from imagery from NASA’s Messenger spacecraft is also available. Mercury’s equatorial diameter is only one third of that of Earth, so it’s quite the little guy. But, he’s also twice as big as Jupiter.
Mercury orbits the sun in an unusual way – it rotates on its axis twice for every two solar revolutions. This causes it to appear as though it’s rotating more than twice a day. That’s a lot of spin for a small planet! Mercury’s elongation is less than three times smaller than Mercury’s, but the distance between the planet and the sun makes it seem closer than it is.
From smallest to largest, Venus is the second planet from the sun and the hottest. With its high levels of carbon dioxide, its atmosphere can be highly toxic. Temperatures on Venus can exceed four hundred degrees Celsius (900 degrees Fahrenheit). Its distance from the Sun, 3,959 miles, and average pressure make Venus the hottest planet in our solar system. Earth is the third nearest planet to the sun and takes 365 days to complete one orbit around the sun.
Our solar system consists of eight planets, ranging in size from the smallest to the largest. The first four planets are Mercury, Earth, and Venus, and go in increasing order of diameter. The outermost planet, Neptune, is the closest to the sun and has the smallest diameter, whereas the largest planet, Jupiter, has the largest radius and is the most distant from the sun. Although Pluto is no longer considered a planet, its moon, Europa, is the largest.
The smallest planet in the solar system, Mercury, resembles the moon with craters, rocky mountains, and a thick atmosphere. Its surface is wrinkled, suggesting that it was formed by volcanic activity. Venus is also the hottest planet, but it is so close to the sun that it lacks an atmosphere to retain heat. This is why it is so hot! The only planet known to have life is Earth.
There are three main types of terrestrial planets: Venus, Earth, and Jovian. The Jovian planets have been the target of many explorations and are the largest and smallest of the planets in our solar system. In order to qualify for planetary status, a planet must meet the following criteria:
The Sun is the biggest object in the solar system. It is 109 times larger than the diameter of Earth, and its volume is about one million times larger. In fact, if all of the Earth’s moons were piled up, the Sun would fit inside. Earth is the fifth largest planet in our solar system, and it is the largest of the inner rocky planets. Jupiter and Saturn have a radius of 695,000 kilometers or 432,000 miles, while the Sun has a diameter of approximately 1.3 million times that of the Earth.
The inner planets are studied by comparing their properties to those of Earth. This process is called comparative planetology. Compared to the Earth, the inner planets can be more easily studied. For example, the Earth has a thicker atmosphere than the Moon. Mars has a larger moon, but it is not the largest one in the solar system. In the inner planets, the most dense and geologically active bodies are in our solar system.
The seventh planet from the sun is Mars. It is approximately half the size of Earth. Although Mars is made mostly of rust-colored rock and dust, it does have a few notable features. One of the biggest is the Olympus Mons volcano, which is three times higher than Mount Everest. Despite its small size, Mars was likely once covered with large amounts of liquid water. Its gravity is only 38 percent of that of Earth, which makes it impossible for humans to live on Mars.
Pluto is no longer classified as a planet, but it has a diameter of 88,700 km (31,411 miles). Other planetary bodies are even smaller than Mars. Venus, for example, has a diameter of 12,742 km (7,917.5 mi), and Mars is the second-smallest planet in the solar system. But even though Earth is the smallest of the planets, it is the fourth largest in the solar system.
The size of planets is a matter of measurement. Mercury, for example, is the smallest planet in our solar system, with a diameter of 4,879 km. Jupiter, on the other hand, is the largest. The three planets are in order from largest to smallest. Mars is the smallest planet in our solar system, but Jupiter is the biggest. There are many dwarf planets in our solar system, but only three are recognized by the International Astronomical Union.
The largest planet in our solar system is Saturn, a giant ringed planet that orbits the Sun every 30 years. The gasses that make up Saturn’s clouds are hydrogen, helium, and methane. Like Jupiter, Saturn rotates extremely fast. It completes one rotation every 11 hours. This gives it an appearance similar to Jupiter’s. The atmosphere of Saturn is also similar to Jupiter’s.
The outer planets are referred to as gas giants. They are large and are made up of hydrogen and helium, and have many or few moons. Jupiter is the largest gas giant, with a radius of 44,423 miles (71492 km). More than one hundred Earths could fit inside Jupiter. Saturn is the second largest planet, with a radius of 37,449 miles (60268 km). Its rings would stretch the width of a credit card.
In order from smallest to largest, Saturn is the brightest planet. Its faintest ring is 300,000 miles long. Uranus and Neptune are the seventh and eighth planets in our solar system. Each of these planets has a different size and radii, but they are all relatively close. The dwarf planet Pluto is the smallest, at only 715 miles (1150 km).
Uranus is the third-largest planet in the solar system and is slightly larger than Neptune. It has a radius of about 15,759 miles and is almost four times as massive as Earth. It takes about 84 Earth years to complete its orbit around the Sun. The ice within the planet’s interior make up more than nine percent of its mass. This makes Uranus the coldest planet in the solar system.
When the Sun first formed, Uranus formed with the other planets. The planets were forming soon after the Sun was born. The planets’ inclinations and orbital eccentricities are the result of gaseous drag removing energy from the planetary orbits during formation. Since the planets are so close together, they resemble each other in appearance and size. The closest planet to the Sun, Pluto, is nearly one-third the size of Uranus.
The atmosphere on Uranus is the coldest in the Solar System. It has a minimum temperature of 49 K, which is the same as the temperature on Earth’s surface. It also has a complex layered cloud structure that consists of water and methane. Lastly, the interior of Uranus is mostly made of rock and ices. The smallest planets in the Solar System are not as large as the Sun, but their atmospheres are just as cold.