facts about our universe

Facts About our Universe

List of Facts About Our Universe & Galaxies

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

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Our UniverseFacts About our Universe, Galaxies, Milky Way and Stars
Big BangAbout 14 billion years ago, our universe was created by the so-called Big Bang.
Milky WayThe spiral shaped galaxy in which we live with about 200 billion stars. Size: Approximately 100,000 light years across.
StarsAround 6,000 stars (i.e. suns) are visible with the naked eye in the night sky.
Our universeThe 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 year186,282 miles (300,000 km) per second = 1 light year = 6 trillion miles (9.46 trillion km)
Our solar systemIn our solar system 8 planets, 5 dwarf planets (e.g. Pluto) 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 sunThe four so-called “inner planets“, closest to the sun are:
  • Mercury
  • Venus
  • Earth
  • Mars

Furthest away from the sun are the four “outer planets“:

  • Jupiter
  • Saturn
  • Uranus
  • Neptune
Dwarf planetsWe currently know of 5 dwarf planets:
  • Eris
  • Ceres
  • Haumea
  • Makemake
  • Pluto (demoted from a planet to a dwarf planet in 2006)
MoonThe largest moons of our solar system are:
  1. Ganymede (Jupiter)
  2. Titanium (Saturn)
  3. Callisto (Jupiter)
  4. Io (Jupiter)
  5. The Moon (Earth)
GalaxiesIt is estimated that there are more than 100 billion galaxies in the universe.
UniverseThe universe is continuously growing and expanding.
Alpha CentauriAlpha Centauri, the closest binary-star system, is 4.3 light years from the Sun.
Shooting starsSmall rock particles that burn up in the atmosphere upon entry.
MeteoritesFist-sized (or larger) chunks of rock or iron that do not completely burn up upon entry.
AsteroidsMinor 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.
CometsCelestial “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.
HalleyHalley‘s comet appears every 76 years. It is due again in 2061.
SatellitesIn 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 touristDennis Tito, American multimillionaire, and former rocket scientist, was the first to spend a holiday in space on board the ISS in April 2001.

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