if the moon is moving 38mm away from the earth every year, how is the earth millions of years old? how did life survive

Question: if the moon is moving 38mm away from the earth every year, how is the earth millions of years old? how did life survive when the moon was closer because the tides would've been so strong?
- Keywords:
  earth,
  moon,
  survive
Asked by anon-191322 to Kathryn, Graeme, Chris, Anne, Agnes, Adam on 5 Nov 2018.
- Anne Green answered on 5 Nov 2018: last edited 5 Nov 2018 10:12 pm
  
  The change in the distance from the Earth to the Moon is actually pretty small, even over millions of years. The average distance today is 384 000 km. (assuming that the rate at which it changes stays constant at 38 mm per year) it would only change by 38 km in a million years, so the change in the tides wouldn’t be huge.
- Agnes Wojtusiak answered on 5 Nov 2018: last edited 6 Nov 2018 4:31 pm
  
  I believe you’re talking about this: https://www.bbc.co.uk/news/science-environment-12311119
  It’s an awesome question, but, sadly, the truth is: I don’t know (but I can try to guess!)
  .
  The earth was not always a nice place to live, it used to be a huge hot rock, and at another point it was quite icy… Yet life survived through that. Also, the early life was just a few cells that can survive deep under water or in very hot places… The first mammals, for example, didn’t appear until 160 million years ago (the earth is about 4.5 BILLION years old).
  .
  If the moon was always moving away at this speed, the distance it moved in that time would have been 6080km, which is about 1.5% of it’s current distance from the earth – is that large enough to make a difference? I don’t know. Was it always moving at the same speed? I don’t know. I tried to quickly search some scientific papers on it, but couldn’t find much – maybe this is something YOU could answer in the future!
- Kathryn answered on 6 Nov 2018:
  
  The moon actually formed after the Earth did meaning that the moon is younger than the earth. The moon formed by a giant impact between an early Earth (molten ball of rock) and a Mars-sized Planet (we called Thia) and the impact actually removed part of the early earth. This material then came together to form the moon. Since then the Orbit has changed and now yes the interaction of the angular moment of the Earth is having an effect on the Earth-Moon system meaning that is is moving away but only with the current configuration of the plates. Two body interactions through orbits, gravity and angular momentum is such an interesting and complex idea to understand the variation in the volume of water as the earth cools and heats up has an effect on it. The gravity forms the sun being in another aspect. A really great question.
  
  LIfe adapts, some life does not survive and dies, but the tides are not the only thing that changed over the Earth history, climate, landmass, temperature all helped life to adapt and evolve to what we have today. If one thing was different life could be very different today.
  
  Great question. Keep thinking like this!
- Adam McGuinness answered on 6 Nov 2018:
  
  I also don’t know! I think that the moon was caused by something huge slamming into the Earth when it was very young, so the material that made the moon would have been thrown quite far away, even as it was being created!
  
  As for how did life survive the strong tides, life can survive some craaaazy extreme situations, did you know that some animals, called tardigrades (or, more cute version, water bears) have been exposed to the vacuum of space, for 10 days, and been fine when they came back to earth! (https://www.newscientist.com/article/dn14690-water-bears-are-first-animal-to-survive-space-vacuum/) Bacteria can also survive in space, which is why NASA have to keep their Mars probes super clean, to avoid putting our bacteria on Mars.
  
  There are a whole group of organisms that live in extreme situations, known as extremophiles, which live in conditions ranging from 100 degrees celsius, to super strong acids (https://en.wikipedia.org/wiki/Extremophile)
- Graeme Poole answered on 7 Nov 2018: last edited 7 Nov 2018 2:48 pm
  
  Yes the Moon formed when a Mars-Sized object hit the Earth 4450 million years ago. The debris form the collision orbited around the Earth and eventually formed the Moon and the Moon was very close to the Earth. It would have looked massive in the sky!!
  
  The Earth was still molten at this point so no life could have existed. There was no water or oceans but the Moon was so close that there were tides of boiling lava instead!!
  
  After about 500 million years the Earth cooled and the Moon had moved away a bit, and so the lava tides stopped and life was able to start. But the Moon has been moving away ever since and will eventually escape the Earth’s gravity and leave us completely!!