How much of the solar system's mass is in the Sun?
The Sun contains about 99.8% of all the mass in our solar system.
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Space Object Facts
Space object facts and facts about space object, from the Random Facts shelf.
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How long does sunlight take to reach Earth?
Sunlight takes about 8 minutes and 20 seconds to reach Earth, so we always see the Sun as it was a few minutes ago.
How many Earths could fit inside the Sun?
About 1.3 million Earths could fit inside the Sun.
How hot is the Sun's core?
The Sun's core is about 27 million degrees Fahrenheit (15 million degrees Celsius).
Why is the Sun's corona hotter than its surface?
The Sun's outer atmosphere, the corona, is hundreds of times hotter than its surface, and scientists are still working out exactly why.
What color is the Sun?
The Sun is called a yellow dwarf, but it actually gives off white light. It looks yellow from Earth because of our atmosphere.
What is the fastest human-made object?
NASA's Parker Solar Probe became the fastest human-made object and flew closer to the Sun than any spacecraft before it, passing about 3.8 million miles from the surface in December 2024.
How old is the Sun?
The Sun is about 4.6 billion years old, roughly halfway through its life.
How long does light take to escape the Sun's core?
Energy made in the Sun's core can take tens of thousands of years or more to work its way to the surface.
What is the solar cycle?
The Sun goes through a cycle of about 11 years in which its activity rises and falls.
Is the Moon moving away from Earth?
The Moon is drifting away from Earth by about 3.8 centimeters a year.
Why do we always see the same side of the Moon?
The Moon is tidally locked to Earth, which means it always shows us the same side.
How did the Moon form?
Scientists think the Moon formed from debris after a Mars-sized object crashed into the young Earth.
Does the Moon have earthquakes?
The Moon has "moonquakes."
What does Moon dust smell like?
Apollo astronauts said Moon dust smelled like spent gunpowder.
Did Apollo leave mirrors on the Moon?
Apollo astronauts left mirrors on the Moon that scientists still bounce lasers off to measure its distance.
How strong is gravity on the Moon?
Gravity on the Moon is about one-sixth as strong as on Earth.
What are Moon trees?
"Moon trees" were grown from seeds that orbited the Moon on Apollo 14.
Is there water on the Moon?
There's water ice in shadowed craters near the Moon's poles.
When did a spacecraft first land on the far side of the Moon?
China's Chang'e 4 made the first landing on the far side of the Moon in 2019.
Is Mercury the hottest planet?
Mercury is the closest planet to the Sun, but Venus is hotter.
Is a day on Mercury longer than its year?
From sunrise to sunrise, one day on Mercury lasts about 176 Earth days, twice as long as its 88-day year.
Is there ice on Mercury?
NASA's MESSENGER spacecraft found water ice in shadowed craters at Mercury's poles.
Is Mercury shrinking?
Mercury is slowly shrinking as its core cools.
Does Mercury have moons?
Mercury has no moons.
What is the smallest planet?
Mercury is the smallest planet in our solar system.
How extreme are Mercury's temperatures?
Mercury's temperatures swing from about 800°F during the day to about −290°F at night.
What is a transit of Mercury?
A transit of Mercury happens when Mercury passes in front of the Sun as seen from Earth.
What is BepiColombo?
BepiColombo, a joint European and Japanese mission, is scheduled to enter orbit around Mercury in late 2026.
How did Mercury help prove relativity?
Mercury's orbit helped confirm Einstein's theory of general relativity.
What is the hottest planet?
Venus is the hottest planet in the solar system, about 900°F at the surface.
Does Venus spin backward?
Venus spins backward compared with most planets, so on Venus the Sun rises in the west.
Is a day on Venus longer than its year?
A day on Venus, about 243 Earth days, is longer than its year of about 225 Earth days.
How strong is the air pressure on Venus?
The air pressure on the surface of Venus is about 90 times stronger than on Earth.
How long did the Venera 13 lander survive?
The Soviet Venera 13 lander survived for 127 minutes on the surface of Venus in 1982.
Why is Venus called the morning star?
Venus is called the "morning star" and "evening star" because it's so bright near sunrise and sunset.
Who is Venus named after?
Venus is the only planet named after a female figure, the Roman goddess of love.
What was the Venus phosphine controversy?
In 2020, scientists reported phosphine in Venus's clouds as a possible sign of life, but the finding has been heavily debated.
What are Venus's clouds made of?
Venus's clouds are made of sulfuric acid.
Who are Venus's surface features named after?
Most features on Venus are named after women.
What is the tallest volcano in the solar system?
Mars's Olympus Mons is about three times taller than Mount Everest.
What is Valles Marineris?
Valles Marineris, a canyon system on Mars, is about as long as the US is wide.
What will happen to Mars's moon Phobos?
Mars's moon Phobos is slowly spiraling inward and is expected to break apart or crash into Mars in tens of millions of years.
What was the first powered flight on another planet?
NASA's Ingenuity helicopter made the first powered flight on another planet, on Mars in 2021.
What color are sunsets on Mars?
Sunsets on Mars appear blue.
How long is a year on Mars?
A year on Mars is about 687 Earth days.
Can dust storms cover all of Mars?
Dust storms on Mars can cover the entire planet.
Why was the Mars Climate Orbiter lost?
NASA lost the Mars Climate Orbiter in 1999 because one team used imperial units and another used metric units.
What are Mars's ice caps made of?
Mars's polar ice caps contain both water ice and frozen carbon dioxide.
Have pieces of Mars landed on Earth?
Meteorites from Mars have been found on Earth.
How big is Jupiter?
Jupiter is the largest planet, and more than 1,300 Earths could fit inside it.
What is the Great Red Spot?
Jupiter's Great Red Spot is a storm bigger than Earth that has lasted for centuries, though it has been shrinking.
Which planet has the shortest day?
Jupiter has the shortest day of any planet, about 10 hours.
What is the largest moon in the solar system?
Jupiter's moon Ganymede is the largest moon in the solar system, and it's even bigger than Mercury.
What is the most volcanic place in the solar system?
Jupiter's moon Io is the most volcanically active place in the solar system.
Does Europa have an ocean?
Jupiter's moon Europa likely has an ocean beneath its icy surface, and NASA launched the Europa Clipper mission in 2024 to study it.
What hit Jupiter in 1994?
Fragments of Comet Shoemaker-Levy 9 crashed into Jupiter in 1994.
Does Jupiter have rings?
Jupiter has faint rings.
Were LEGO figures sent to Jupiter?
NASA's Juno spacecraft carried three LEGO figures to Jupiter.
Which planet has the strongest magnetic field?
Jupiter has the strongest magnetic field of any planet.
Could Saturn float in water?
Saturn is less dense than water, so it would float in a large enough bathtub.
How thick are Saturn's rings?
Saturn's rings are mostly ice and are surprisingly thin, often only about 30 feet thick.
What is Saturn's hexagon?
A six-sided storm called the hexagon swirls at Saturn's north pole.
Which planet has the most moons?
Saturn has the most known moons of any planet.
What is Titan?
Saturn's moon Titan has a thick atmosphere and lakes of liquid methane, and the Huygens probe landed there in 2005.
Does Enceladus have geysers?
Saturn's moon Enceladus shoots geysers of water into space.
Will Saturn's rings disappear?
Saturn's rings are slowly falling into the planet and could disappear in a few hundred million years.
Why did Saturn's rings seem to vanish in 2025?
Saturn's rings appeared to nearly vanish from Earth's view in 2025 because they were tilted edge-on to us.
How did the Cassini mission end?
NASA's Cassini spacecraft ended its mission in 2017 by diving into Saturn.
What is Dragonfly?
NASA's Dragonfly mission will send a drone to Saturn's moon Titan.
Why does Uranus spin on its side?
Uranus is tilted about 98 degrees, so it basically rolls around the Sun on its side.
What was the first planet discovered with a telescope?
Uranus was the first planet discovered with a telescope, by William Herschel in 1781.
What did Herschel want to name Uranus?
William Herschel wanted to name Uranus "George's Star," after King George III.
Which planet has the coldest atmosphere?
Uranus has the coldest atmosphere of any planet, reaching about −371°F.
Has any spacecraft visited Uranus?
Only one spacecraft, Voyager 2, has visited Uranus, in 1986.
What does Uranus smell like?
Uranus's clouds contain hydrogen sulfide, which would make them smell like rotten eggs.
When were Uranus's rings discovered?
Uranus's rings were discovered in 1977.
How long are seasons on Uranus?
Each season on Uranus lasts about 21 Earth years.
Does it rain diamonds on Uranus?
Scientists think it may rain diamonds deep inside Uranus.
Why is Uranus blue-green?
Uranus gets its blue-green color from methane in its atmosphere.
How was Neptune discovered?
Neptune was discovered in 1846 after mathematicians predicted its location from its gravitational pull on Uranus.
Which planet has the strongest winds?
Neptune has the strongest winds in the solar system, up to about 1,200 miles per hour.
What is unusual about Neptune's moon Triton?
Neptune's largest moon, Triton, orbits backward and will eventually be torn apart by Neptune's gravity.
When did Neptune complete its first orbit since its discovery?
A year on Neptune is about 165 Earth years, and in 2011 it completed its first orbit since being discovered.
Has any spacecraft visited Neptune?
Only one spacecraft, Voyager 2, has visited Neptune, in 1989.
What happened to Neptune's Great Dark Spot?
Neptune's Great Dark Spot, a huge storm seen by Voyager 2, later disappeared.
Did Galileo see Neptune?
Galileo saw Neptune in 1612 but thought it was a star.
Does Triton have geysers?
Neptune's moon Triton has geysers of nitrogen.
What is the farthest planet from the Sun?
Neptune is the farthest planet from the Sun.
Are Neptune and Uranus really different colors?
A 2024 study found that Neptune and Uranus are closer in color than older images suggested.
When was Pluto reclassified?
The International Astronomical Union reclassified Pluto as a dwarf planet in 2006.
Who named Pluto?
Pluto was named by Venetia Burney, an 11-year-old girl in England.
Does Pluto have a heart?
NASA's New Horizons spacecraft revealed a heart-shaped region on Pluto in 2015.
Whose ashes are on the New Horizons spacecraft?
Some of the ashes of Clyde Tombaugh, who discovered Pluto, are on the New Horizons spacecraft.
Has Pluto completed an orbit since it was discovered?
Pluto takes about 248 Earth years to orbit the Sun, so it hasn't completed a full orbit since it was discovered.
What is Charon?
Pluto's moon Charon is about half the size of Pluto.
Is Pluto smaller than the Moon?
Pluto is smaller than Earth's Moon.
Which state declared Pluto a planet?
Illinois passed a resolution declaring Pluto a planet in 2009.
What color is Pluto's sky?
Pluto has blue skies.
Is Pluto ever closer than Neptune?
Pluto was closer to the Sun than Neptune from 1979 to 1999.
How many stars are in the Milky Way?
The Milky Way contains an estimated 100 billion to 400 billion stars.
How big is the Milky Way?
The Milky Way is about 100,000 light-years across.
How long does it take the solar system to orbit the Milky Way?
Our solar system takes about 230 million years to orbit the center of the Milky Way.
Will the Milky Way crash into Andromeda?
The Milky Way is expected to merge with the Andromeda Galaxy in about 4.5 billion years.
Where does the name "Milky Way" come from?
The name "Milky Way" comes from a Greek myth about the goddess Hera's milk.
What does the center of the Milky Way smell like?
Scientists found ethyl formate, the chemical that helps give raspberries their flavor, in a dust cloud near the center of the Milky Way.
Can most Americans see the Milky Way?
About 80% of Americans can't see the Milky Way because of light pollution.
What did the Gaia mission map?
The European Space Agency's Gaia mission mapped about two billion stars in the Milky Way.
What shape is the Milky Way?
The Milky Way is a barred spiral galaxy.
What is the Local Group?
The Milky Way is part of a group of galaxies called the Local Group.
What is at the center of the Milky Way?
A supermassive black hole called Sagittarius A*, about 4 million times the mass of the Sun, sits at the center of the Milky Way, and its first image was released in 2022.
When was the first image of a black hole taken?
The first image of a black hole, in the galaxy M87, was released in 2019.
What is spaghettification?
"Spaghettification" describes how a black hole's gravity would stretch an object into a long, thin strand.
Who popularized the term "black hole"?
Physicist John Wheeler popularized the term "black hole" in 1967.
When were gravitational waves first detected?
Gravitational waves from two merging black holes were first detected by LIGO in 2015.
Who won the 2020 Nobel Prize for black hole research?
Roger Penrose, Reinhard Genzel, and Andrea Ghez won the 2020 Nobel Prize in Physics for black hole research.
Would Earth get sucked in if the Sun became a black hole?
If the Sun were replaced by a black hole of the same mass, Earth's orbit wouldn't change.
What was the first black hole discovered?
Cygnus X-1 was the first object widely accepted as a black hole.
Does time slow down near a black hole?
Time slows down near a black hole.
Did the movie "Interstellar" contribute to science?
The black hole visuals created for the movie "Interstellar" led to a published scientific paper.