# @science on Instagram

- **Type:** Image
- **Original URL:** https://www.instagram.com/p/DRkj7qAE2Ld
- **Gondola URL:** https://gondola.cc/posts/37343849-science-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/7ae380c80a.jpg
- **Posted:** 2025-11-27T19:15:14.000+00:00
- **Account Owner:** Science 🧬 (@science) — https://gondola.cc/science

## Caption

To estimate how many planets there are in the universe, we will need three numbers. First, we need to estimate how many planets are for one star. Secondly, we need to estimate how many stars there are in the galaxy. Thirdly, we need to estimate how many galaxies there are in all space. Professor Ethan Siegel and assistant professor David Kipping took up this challenge and tried to determine the number of all planets in space.⁠
Obviously, it's hard to give a precise number, so we should stick to an absolute pessimistic scenario in each of the three variables.⁠
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Studies from 2016 have shown that there are at least 2 trillion galaxies in the observable universe. According to scientists, the number of stars in the Milky Way ranges from 100 to 400 billion. Other galaxies have much, much more, and others have less. David Kipping assumes a pessimistic scenario, according to which one planet would correspond to one star. Let's assume that there is, in fact, only one planet per star. Let's assume that the average number of stars in the galaxy is only 100 billion. Let's assume that there are 2 trillion galaxies in the universe.⁠
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So, how many planets are there?⁠
20 sextillions. 200.000.000.000.000.000.000.000. Quite a lot. So, how many seconds have passed since the Big Bang? The universe was formed 13.8 billion years ago. Each year contains 31,536,000 seconds. This means that 435.196.800.000.000.000 seconds have passed since the Big Bang. 200.000.000.000.000.000.000.000 is a much bigger number. So even if we take a pessimistic scenario, there are still many more planets in space than in seconds since the creation of the universe.⁠
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#universe #planets #galaxies #bigbang #milkyway #milkywaygalaxy #space #astronomy #science⁠

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## Tags

science, galaxies, planets, universe, space, milkyway, bigbang, milkywaygalaxy, astronomy

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