Science fiction can be a strange prescient. Although "Star Trek," "Star Wars," and "Lost in Space" all describe life on other planets in distant solar systems, scientists have no evidence that was any other planets outside our solar system until 1992, when the first exoplanet was discovered. That means that these films and TV shows, dating back to 1992, predicted the discovery of the diversity of planets and moons that exist in our vast universe. the most profound questions about our existence, especially: are we unique in the universe? Does life exist on Earth because our solar system and planet are special, and an unlikely event of events that led to our existence? Or rather, are solar systems with bodies like Earth common, meaning we are just an unusual example of a wealthier planet? Titled "When the World Has Two Months," Asphaug's book is a historical, essential, source of our solar system. Although a story that has remained in flux as science has changed, Asphaug talks about how observation and simulation combine with some of the theories that approach the realm of certification ̵1; that is, the notion that the moon of Earth is created when a Mars-sized planet named Theia struck a glowing blow to the proto-Earth, removing huge amounts of rock that eventually connected to what we called "The Moon."
I talked to Dr. Asphaug by phone about the origins of the Moon, and why life as we know it on Earth seems to rely on this humble locked news.
Keith A. Spencer: I remember as a kid growing up in the 1990s, we didn't really know there were planets in other solar systems. Now that we've noticed so much, my question for you is: how unique is our solar system? How big is the Earth?
Dr. Erik Asphaug : That's kind of the key question today in astronomy. We have all this raw data from the Kepler Telescope – it has one hundred and fifteen megapixel cameras staring at a bunch of stars, and then when one of those pixels is blurred, that's a sign that a planet passes in front of a star.
This is accurate data, but also very biased w hen you think about it – the stars just happen to have a planet glowing in front of them during mission time like three years. So it is kind of biased to find objects that are, like, large Jupiter-sized planets near [to their parent stars].
So if you look at only raw data – you outline all the planetary systems we know about – it's just mind blowing. We didn't know any of this in the 1990s or earlier. F or, for example, in the late 1960s and 1970s, the ruling hypothesis for our own solar system forming was that another star was about to collide with our star – and it was like an accidental accident, and [this] is why we have planets [and] no other planets.
It's true that if you if you plotted the planets we knew against us, we would not seem right. Most of the [exo] planets [we’ve observed] orbits [their stars closer than] Mercury are made of our star. Which is kind of weird to think about – you know, planets two or three times the mass of Jupiter orbiting their star every five days. That's a pretty unusual planet, apparently. And that's not what we observed in our solar system, where we see the tiny dribble of planets just a little further away from our star – f that was when liquid water was found – and then the Jupiter is at five times the distance of the earth, and then Saturn is ten times the distance of the earth, and these giant icebergs are still far away – and that's still an anomaly. But then, you have to remember, we probably haven't discovered the planets yet around those stars [with our telescopes like Kepler]. Jupiter orbits every 10 Saturn or every 30 years. Neptune, Uranus you know a hundred years or so – so that's kind of how long it takes to have luck to happen to see one of the kinds of planets passing before their stars.
So you're saying that there is a bias option in our list of exoplanets to follow? Like, can we easily see orbits really close to their stars?
A completely. And astronomers – data collaborators, observers – get a handle on this, but it looks like it's kind of anomalous.
What is the current scientific theory of what is here before our solar system, and how do we know that?
You know when you look at the nearby universe, in our small space sector where we see well in telescopes, you see dark clouds And you never really notice if you're an astronomer backyard – you think it was just a place where there weren't many stars, but there were actually a lot of stars in [these areas]. In the infrared you can see that these clouds are really kind of warm. And it doesn't take a whole lot of math to say, "hey that's a dust cloud that is huge enough in the comfort process."
So it would be like looking at a storm cloud and saying, "hey that's going to be cloudy." That's kind of the test. So we see what the star looks like at first and then we see what it looked like in the early stages, when the star was formed, because they can easily be seen using infrared telescopes.
And the point is, you see this hot gas in or in orbit around these stars, and now you see the gas blob wanting to crumble to become a star – you know the next step. We also see that we see tiny glowing gases in which a star just lights up and is just beginning to emit radiation, it is like a neon tube that emits ultraviolet radiation and emits it. the gas around it, and it shines.
And then the next step is you actually see the discs, and you see a star that starts to burn in the middle of it and can become a sun-like star. And then you see the globs on the disc and you see the gaps on the disc and you're like, "those must be planets." So we saw the process going on, [but] where we were missing the dots was what would happen next. We can't really tell what we are seeing in a time sequence that can say, "this is the next stage," and you can't see much later than that because in the next stage the dust is moving away.
point, the planets are too small, too cold. Nothing to see.
So now it is left to theorists to kind of connect the dots between observations and what we see here in our solar system.
I want to get into the title of the book. It is now widely believed that the Moon was formed when a Mars-sized body, Theia, collapsed on Earth, causing a bunch of things to eject and form a disc around the Earth which eventually merged with the Moon. Why is the science around this theory integrated, and what is the evidence?
If you go back to the Apollo Era, on our way to the Moon, there are two camps of intellectual speaking. One camp thinks that the moon is a primitive object left over from the formation of the solar system, which the Earth did not create. Remember, there wasn't a lot of computer-modeling back then – nothing. So people just have to use pen and paper to see if things make sense.
We have known for over one hundred years that the moon is less dense than Earth. It gained a density of about three-fifths of the Earth. That's about the thickness of the meteorite.
The other camp is a bit more physics-based and geophysical. They looked at the detailed images of the craters and saw what they suspected was widespread volcanic activity near the moon. Maths asks, "OK let's say you want to get the moon, what does that mean?" And it's kind of where the Giant Impact Theory comes along, supported, as you said, completely behind the theory. You know you're trying to make sense of little scraps of data and you know what the models are saying, "hey I think getting the moon is a great idea let's do this." And they try to make it home for a close encounter with the earth and to do that as if the Earth has a wide environment maybe you can slow it down correctly. .. But when they try to model it, the Moon will just break.
So don't say with the Capture Hypothesis, there is no way to make the model – which means scientists are beginning to think, "maybe something else happened," right?
Exactly. I think there is a bias against admitting the Giant Impact Hypothesis – no one wants to think of something that hit Earth and possibly break it. You can ruin it!
This is a very dangerous event that results in the whole planet but does not destroy it [the Moon or Earth]. And the idea of the Moon being formed in this way was never really in the forefront of anyone's mind on the Apollo missions – the Apollo missions only proved that the moon was volcanic. But that gave us permission to imagine the moon being formed in a very powerful way. And that led people to pay attention to this theory, and then computational power came of age and that was really a science story in the 80s. The Giant Impact Theory is that you really know a science story that follows what computers tell us.
It's interesting when you think about it that we're the only terrestrial planet with a big moon. I mean, Mars has glorified captured asteroids [Phobos and Deimos] but no other terrestrial planet has a moon like ours. I think back to the similarity of choice bias you mentioned earlier – we are here in this world, so it's hard for us to have a sense of how strong or normal we are, right? I know the moon has some protective and stabilizing effects for us on Earth, and it could make the planet more comfortable. Do we owe the Moon?
That's the main question, and the more we look at it in detail, the more it goes on. If you think about the Moon and theories for the origin of life – well, as you said, the moon is stabilizing the Earth [‘s rotation]. So we do not get periods that are violent, [the axial tilt] not more than or less than 23.5 degrees. If you don't have the moon there, the Earth can do well at doing what Mars does every five million years or so – Mars ends up with the sun on its side, and goes through crazy times where the poles focus on the Sun, and then turn again.
So it's not Earth that has this moon stabilized this axis of rotation, it is raising ocean waters, that is, you know, if not a source incubator of life, certainly a source for spawning life.
Then there are these kinds of cosmic objects – such as the fact that the moon covers the sun precisely [during an eclipse]. I'm doing something about this book, because [a total solar eclipse] is the most remarkable thing any human could ever see. Why is it like this? I don't know if it has anything to do with life, but it can be conscious. I wonder – it's like a sign, a symbol of something that could trigger some kind of self-awareness that occurred in the Stone Age.