Facts About our Universe


List of Facts About Our Universe & Galaxies 🌌

Fascinating facts about our Universe, the Milky Way, the Galaxy and our solar system.

  • ADDucation’s list of facts about the universe was compiled by Robert Junker and last updated on 18 Aug 2024

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Our Universe 🌌 Facts About our Universe, Galaxies, Milky Way and Stars
Big Bang About 14 billion years ago, our universe was created by the so-called Big Bang.
Milky Way The spiral shaped galaxy in which we live with about 200 billion stars. Size: Approximately 100,000 light years across.
Stars Around 6,000 stars (i.e. suns) are visible with the naked eye in the night sky.
Our universe The universe is about 13.8 billion years old which equates to a radius of about 13.8 billion light-years so you’d think that the diameter is nearly 28 billion light-years. That’s what can be seen, but the universe is constantly expanding so the diameter is actually some 92 billion light-years.
Light year 186,282 miles (300,000 km) per second = 1 light year = 6 trillion miles (9.46 trillion km)
Our solar system In our solar system 8 planets (see below), 5 dwarf planets (see below) and millions of so-called small bodies (comets, asteroids and meteorites) orbit around the sun. Our solar system ends with the Kuiper Belt (where Pluto is located) and the “Oort cloud”.
Planets around the sun The four so-called “inner planets“, from closest to farthest away from the sun in our solar system, are:
  • Mercury
  • Venus
  • Earth
  • Mars.

Further away from the sun are the four “outer planets“, from closest to farthest from the sun, are:

  • Jupiter
  • Saturn
  • Uranus
  • Neptune.
Dwarf planets We currently know oof 5 dwarf planets in our solar system:
  • Eris
  • Ceres
  • Haumea
  • Makemake
  • Pluto (demoted from a planet to a dwarf planet in 2006).
Moon The 5 largest moons of our solar system are:
  1. Ganymede (orbiting Jupiter)
  2. Titanium (orbiting Saturn)
  3. Callisto (orbiting Jupiter)
  4. Io (orbiting Jupiter)
  5. The Moon (orbiting planet Earth).
Galaxies Until recently our best estimate as 170 billion galaxies in the universe but the latest estimate is two trillion galaxies in the universe.
Universe The universe is continuously growing and expanding.
Alpha Centauri Alpha Centauri, the closest binary-star system, is 4.3 light years from the Sun.
Shooting stars Small rock particles that burn up in the atmosphere upon entry.
Meteorites Fist-sized (or larger) chunks of rock or iron that do not completely burn up upon entry.
Asteroids Minor planets that move in an orbit around the sun. 542,700 asteroids are identified but the actual number is much larger. The last significant asteroid impact occurred on 30 June 1908 in the Siberian region of Tunguska.
Comets Celestial “dirty snowballs” of gas and ice which travel through the solar system in various periodic orbits. Around 5000 comets are currently identified with more being discovered all the time.
Halley Halley‘s comet appears every 76 years. It is due again in 2061.
Satellites In addition to almost 900 active satellites there’s around half a million pieces of space junk (old satellites, rocket parts, etc.) orbiting the Earth. Over 21,000 objects over four inches (~100mm) diameter are constantly tracked by the US Department of Defense.
The first space tourist Dennis Tito, American multimillionaire, and former rocket scientist, was the first to spend a holiday in space on board the ISS in April 2001.

See also: All Planets in the Solar System… | Earth & Space…

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