40 Fun Facts About Solar System & Space

Which planet is known as the Red Planet?

Mars is the Red Planet: its colour comes from dust and sand rich in reddish iron oxides, essentially rust, spread across its plains.

How many planets are in our solar system?

The count fell from nine to eight when Pluto was reclassified as a dwarf planet in 2006.

Which planet is closest to the Sun?

Mercury is the closest planet to the Sun, orbiting at an average distance of about 57.9 million kilometers.

Who was the first human to travel to space?

Soviet cosmonaut Yuri Gagarin became the first human in space on April 12, 1961, completing one orbit of Earth aboard the Vostok 1 spacecraft in a flight lasting 108 minutes.

In what year did Apollo 11 land humans on the Moon for the first time?

Apollo 11 landed on the Moon on July 20, 1969. Neil Armstrong became the first person to step onto the lunar surface, followed by Buzz Aldrin 19 minutes later.

What is the hottest planet in our solar system?

Despite being farther from the Sun than Mercury, Venus is the hottest planet due to its thick atmosphere of carbon dioxide, which traps heat in a runaway greenhouse effect, pushing surface temperatures above 460°C.

What is the asteroid belt located between?

The asteroid belt is located between the orbits of Mars and Jupiter, roughly 2.2 to 3.2 AU from the Sun. It contains millions of rocky objects believed to be remnants from the early solar system.

Which NASA rover landed on Mars in February 2021 to search for signs of ancient life?

Perseverance landed in Jezero Crater on 18 February 2021 and found evidence of an ancient lake and river delta, caching rock cores for a planned sample return to Earth.

What is the primary composition of the Sun?

By mass the Sun is roughly 73% hydrogen and 25% helium, with only traces of heavier elements such as oxygen, carbon, neon and iron.

Who was the first American woman in space?

Sally Ride became the first American woman in space on June 18, 1983, aboard the Space Shuttle Challenger during the STS-7 mission.

Which space telescope, launched in 2021, primarily observes in infrared wavelengths?

The James Webb Space Telescope (JWST), launched December 25, 2021, observes in infrared wavelengths (0.6-28.5 micrometers). Its 6.5-meter gold-plated mirror gives it six times the light-collecting area of Hubble.

What small helicopter made the first powered, controlled flight on another planet?

NASA's Ingenuity helicopter made the first powered, controlled flight on another planet on 19 April 2021, rising about 3 metres above Jezero Crater on Mars, and completed 72 flights before its mission ended in January 2024.

What is the Great Red Spot?

The Great Red Spot is a giant anticyclonic storm on Jupiter, wider than Earth at roughly 14,000-16,000 km across, and has been tracked continuously since the 1830s.

Who discovered the four largest moons of the biggest planet in 1610?

Galileo Galilei discovered the four largest moons of Jupiter (Io, Europa, Ganymede, and Callisto) in 1610. They are known as the Galilean moons in his honor and were the first moons discovered beyond Earth.

What is the tallest volcano in the solar system?

Olympus Mons on Mars stands about 21.9 km (72,000 ft) high, roughly 2.5 times the height of Mount Everest. It is a massive shield volcano about 600 km wide.

What are the rings of the second-largest planet made almost entirely of?

The ring particles range from micrometres to metres in size and are almost pure water ice with only a trace of rocky material.

What region of the solar system lies beyond Neptune's orbit and contains Pluto?

The Kuiper Belt is a doughnut-shaped region of icy objects that extends from Neptune's orbit (about 30 AU) to roughly 50 AU from the Sun. It is home to Pluto and several other dwarf planets.

What does one astronomical unit (AU) represent?

Since 2012 it has been fixed at exactly 149,597,870,700 metres — about 150 million km, or roughly 499 light-seconds.

Which NASA mission flew past Pluto in 2015, providing the first close-up images?

NASA's New Horizons spacecraft flew past Pluto on July 14, 2015, revealing surprisingly youthful mountains, a heart-shaped nitrogen ice plain, and an unexpectedly complex surface.

What is the largest moon in our solar system?

Ganymede, a moon of Jupiter, is the largest moon in the solar system at 5,268 km across, bigger than the planet Mercury though only about half as massive.

Approximately how far is one light-year?

A light-year is approximately 9.46 trillion kilometers (5.88 trillion miles) — the distance that light travels in one Earth year at a speed of about 300,000 km per second.

Which spacecraft became the first to enter interstellar space?

Voyager 1 crossed into interstellar space on 25 August 2012, about 121 AU from the Sun, and is the most distant human-made object; Voyager 2 followed in November 2018.

Which planet could theoretically float in water due to its low density?

Saturn's average density is about 0.69 g/cm³, roughly 30% less than water, so in an imaginary ocean big enough it would bob on the surface.

What did Neil Armstrong and Buzz Aldrin name their landing site on the Moon?

Armstrong and Aldrin named their landing site Tranquility Base, located in the Sea of Tranquility (Mare Tranquillitatis) on the Moon's surface.

Which planet is tilted almost on its side, with an axial tilt of about 98 degrees?

Uranus spins on an axis tilted about 98 degrees to its orbit, so it rolls around the Sun almost on its side, and each pole gets about 42 years of sunlight followed by 42 of darkness.

Which moon of Saturn has liquid methane lakes on its surface?

Titan is the only body in the solar system besides Earth known to have stable liquid on its surface. Its lakes and seas are filled with liquid methane and ethane, confirmed by the Cassini mission in 2007.

Which dwarf planet is the only confirmed one inside the main asteroid belt?

Ceres was announced as a new planet when Giuseppe Piazzi spotted it on 1 January 1801, then demoted to an asteroid before being promoted again to dwarf planet in 2006.

Which moon in our solar system is the most volcanically active body?

Io has more than 400 active volcanoes, driven by tidal heating as it is squeezed between its giant parent planet and the neighbouring large moons.

In what year were the twin Voyager probes launched?

Both probes launched in 1977 to exploit a rare planetary alignment that occurs once every 175 years, giving humanity its first close-up views of the outer planets.

Which planet has the fastest winds in the solar system?

Neptune has the fastest winds of any planet in the solar system, reaching speeds of up to 2,100 km/h (1,300 mph). This is surprising given Neptune's great distance from the Sun.

What is the largest moon of Pluto?

Charon, discovered by James Christy in 1978, is about 1,212 km across, roughly half Pluto's diameter, so the pair are often called a double dwarf planet; Nix, Hydra, Styx and Kerberos are far smaller.

What is the approximate temperature at the Sun's core?

The Sun's core reaches approximately 15 million degrees Celsius (27 million °F), hot enough to sustain nuclear fusion reactions that power the star.

What hypothetical spherical cloud of icy objects is believed to surround the outer solar system?

The Oort Cloud is a theoretical spherical shell of icy objects that may extend from about 2,000 AU to 100,000 AU (1.5 light-years) from the Sun. It is thought to be the source of long-period comets like Hale-Bopp.

Which planet is the densest in our solar system?

Earth is the densest planet in the solar system with an average density of about 5.51 g/cm³, primarily due to its iron-nickel core.

Which planet has the largest known magnetic field in the solar system?

Jupiter's magnetic field is approximately 20,000 times stronger than Earth's, making it the most powerful of any planet in our solar system. It extends millions of kilometers into space.

Which Saturn moon sprays jets of ice water into space from its south pole?

Enceladus emits dramatic jets of ice particles and water vapor from fractures near its south pole. These plumes suggest a subsurface ocean, making Enceladus one of the most promising places to search for extraterrestrial life.

What is the Hubble Space Telescope's approximate altitude above Earth?

Hubble orbits in low Earth orbit at roughly 560 km (about 540 km by the 2020s, as atmospheric drag slowly lowers it from the 612 km of its 1990 deployment); it logged its millionth observation in 2011.

How far from Earth does the James Webb Space Telescope orbit?

JWST orbits the Sun around the second Lagrange point (L2), about 1.5 million km beyond Earth, where the Sun, Earth and Moon all lie on the same side so its sunshield can block their heat and light.

What was the first spacecraft to orbit another planet?

Mariner 9 entered orbit around Mars on 14 November 1971, narrowly beating the Soviet probes Mars 2 and Mars 3, and had to wait out a global dust storm before mapping the surface.

What is the name of the boundary where the Sun's solar wind gives way to interstellar space?

The heliopause is where the Sun's solar wind is stopped by the interstellar medium, roughly 120 AU from the Sun; inside it lies the heliosphere, the bubble the solar wind inflates.