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Astronomy Galaxies

2 trillion galaxies — the large-scale structure of the universe from local group to cosmic web.

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The observable universe contains approximately 2 trillion galaxies (revised upward from earlier 200 billion estimate by 2016 Hubble Deep Field analysis). Galaxies come in types: elliptical (no star-forming), spiral (like the Milky Way), and irregular. They cluster into groups, superclusters, and filaments — the 'cosmic web' is the largest structure in the universe. The Milky Way is a barred spiral galaxy with 100–400 billion stars, spanning 100,000 light-years. Our nearest large neighbor, Andromeda (M31), is 2.5 million light-years away and will collide with the Milky Way in 4.5 billion years. The James Webb Space Telescope (launched 2021) has revealed galaxies from just 300 million years after the Big Bang — showing the universe formed structure faster than models predicted.

# Top 10 galaxy facts

  1. 12 trillion galaxies
  2. 2Milky Way is average spiral
  3. 3Andromeda collision in 4.5B years
  4. 4supermassive black holes at every galaxy center
  5. 5cosmic web
  6. 6James Webb findings
  7. 7Local Group
  8. 8Virgo Supercluster
  9. 9Great Attractor
  10. 10galaxy classification (Hubble sequence)

Fascinating Facts

  • ◆The James Webb Space Telescope can see a bumblebee at the distance of the Moon — and has used this resolution to photograph galaxies from 300 million years after the Big Bang
  • ◆The Milky Way and Andromeda galaxies will collide in 4.5 billion years — but stars are so spread out that the probability of individual star collisions is essentially zero
  • ◆Light from the most distant galaxies visible to James Webb has been traveling for 13.4 billion years — we see those galaxies as they were before Earth existed
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