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Planet Sizes in the Solar System

Comparing the diameters of the Sun and its orbiting planets *

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* The Sun and Pluto are not considered planets but are shown for perspective purposes.

The planets of the Solar System in perspective

The Sun, the 8 official planets in our solar system (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune) and the dwarf planet Pluto, are each entirely unique in their orbiting patterns, colouring, size, mass, and composition. Given the uniqueness of each planet (and star), we can make some fascinating comparisons that highlight the awe-inspiring characteristics of our solar system. Let’s get started!

The Sun

picture of the Sun Our solar system’s star is classified as a small-to-medium sized star, yet comes in at a whopping 1,329,000 km in diameter and weights approximately 2000 trillion trillion tonnes. That’s not a typo, it really is that heavy. The surface of the sun is a staggering 5500 degrees Celsius, but its core is a nearly inconceivable 15 million degrees Celsius. To put the sun into perspective, here are a few interesting facts:

Mercury

picture of Mercury Mercury is the smallest planet in our solar system, being only 4879.4 km in diameter; that’s roughly the size of our moon. Mercury is 57.9 million km from the sun and is the closest planet to the sun. Mercury is roughly 38% the size of Earth and has a mass of 3.3022 (1023), making the planet roughly 18x lighter than Earth. One day on Mercury lasts for 59 of our Earth days, and its orbit time is 88 earth days. Mercury’s composition consists of iron and silica rocks; this planet contains more iron in its core than any other in our solar system, and has a grey appearance. Here are some interesting facts about Mercury:

Venus

picture of Venus Venus is the second closest planet to the sun and is named after the Roman Goddess of love. Venus is 108.2 million km from the sun and has a diameter of 12,104 km, making it the closest planet in size to Earth. Venus has a mass of 4.8685 (1024) and is abundant in greenhouse gases. To orbit around the sun, Venus takes 225 Earth days. 1 day on Venus is the equivalent of 243 Earth days. That means that a day on Venus is longer than a year. Venus has a reddish-orange appearance and is the hottest planet in our solar system. Here are some cool facts about Venus:

Earth

picture of the Earth Earth is 3rd farthest from the sun and is the only life-sustaining planet that we know of. Due to its rotational axis, we have 4 seasons. Our moon is responsible for the tides and is our only natural satellite. The Earth is 149.6 million km from the sun and has a diameter of 12,756 km. Earth has a mass of 5.9736 (1024) and is roughly 4.6 billion years old. Earth is the densest planet in our solar system, and our atmosphere consists of 78% nitrogen, 21% Oxygen, .93% argon, and 0.03% carbon dioxide. Here are some interesting facts about Earth:

Mars

picture of Mars Mars is the fourth furthest planet from the sun and has an orange appearance. Mars is also the last of the terrestrial planets. Mars’ gravity is 1/3 that of Earth’s, but it would be enough to sustain human life with the help of science and technology. One day on mars is 25 hours, or one sol (Martian day), and Mars’ orbit around the sun takes 669 sols. Mars has a mass of 6.4185 (1024) and has a diameter of 6,779 km, making it 53% the size of Earth. Mars is 227.9 million km from the sun. Here are some interesting facts about Mars:

Jupiter

picture of Jupiter Jupiter is the largest planet in the solar system and is the first of the Gas Giants. Jupiter is 778.3 million km from the sun and has a diameter of 142,800 km, which is more than 11 times the diameter of Earth. Jupiter has a mass of 1.8986 (1027), and is 73x bigger than earth. One day on Jupiter is only 9 hours, though a single orbit around the sun takes 12 Earth years. Here are some interesting facts about Jupiter:

Saturn

picture of Saturn Saturn is the second largest planet in our solar system with a diameter of 120,660 km and a mass of 5.6846 (1026). Saturn is 1,427 million km from the sun and features a large ring comprised of space debris and ice. Saturn’s orbit around the sun takes roughly 30 Earth years and one day on Saturn is 11 hours on Earth. Here are some interesting facts about Saturn:

Uranus

picture of Uranus Uranus is the 7th furthest planet in our solar system and is one of the most unique. Uranus has a severe tilt that puts its equator at a right angle to the orbit, which is believed to be caused by a collision with another planet. Uranus’ core is also thought to be extremely icy rather than molten like the others. Uranus is 2,871 million km from the sun, has a diameter of 51,118, and has a mass of 8.6810 (1025). Here are some interesting facts about Uranus:

Neptune

picture of Neptune Neptune is the furthest planet from the sun, being 4,497.1 million km away. Neptune has a diameter of 49,528 km and a mass of 10.243 (1024). Uranus is composed of hydrogen and helium and is surrounded by a cloud layer with winds faster than the speed of sound (2,100 km per hour). An abundance of methane givens Neptune a brilliant blue colouring. One orbit around the sun takes roughly 165 Earth years, and one day on Neptune is 19 Earth hours. Here are some interesting facts about Neptune:

Pluto

picture of Pluto

Ah, the "famous planet that is not a planet". Perhaps it is not technically considered a "standard" planet. But we still like to include it in our Solar System model.

See also Scaling our Solar System within the Universe