The next time you look at a bright full moon, think about this: No one knows exactly where the moon came from.
“We have no idea why the moon is here,” says science author Rebecca Boyle Inexplicable – Vox’s podcast that explores great mysteries, unanswered questions and all things we learn by diving into the unknown. “I think too many people [the moon] is taken for granted, it’s this kind of silly thing, and galaxies and nebulae and stars and planets are more exciting. “
It is true that some of the most epic questions in science are found in the farthest parts of space – how and when were the first galaxies formed, what happens inside a black hole – but equally epic questions exist here in our heavenly neighborhood, in our own solar system.
To explore our own solar system – the moons and planets in it – is to better understand what is possible in the farthest parts of the universe. Everything we find or discover in our own cosmic backyard will help us understand what is possible in the wider universe. If evidence of ancient life is found in a hostile world such as Mars, we can better understand how ordinary life can be in other solar systems. If we understand how a possibly once living world like Venus fell into ruins, we might understand how often similar planets around other stars die in an apocalypse.
The most provocative solar system mysteries help us understand why we are here, how long we can have left, and what we can leave behind. Here are some of the mysteries of the solar system we have encountered Inexplicable.
For more mysteries, listen and stay tuned Inexplicable wherever you listen to podcasts.
What killed Venus?
“Hellscape” is the most appropriate word to describe the surface of Venus, the other planet from the sun. At 900 degrees Fahrenheit, it is the warmest planet in the solar system, thanks to an atmosphere that consists almost exclusively of carbon dioxide, which generates a very strong greenhouse effect. Clouds made of highly corrosive sulfuric acid are draped over a volcanic landscape of razor-sharp volcanic rock. The pressure on the surface of Venus is about 92 times what you would feel at sea level on Earth.
Yet some scientists suspect that Venus was once very similar to Earth, with a sea of liquid water like those that support life on our planet. This poses an existential question for life on earth.
“Venus and Earth are planetary siblings,” says Robin George Andrews, volcanologist and author of Super Volcanoes: What They Reveal about Earth and the Worlds Beyond. “They were made at the same time and made of the same things, but Venus is apocalyptic and terrible in every possible way. Earth is a paradise. So why do we have a paradise next to a lost paradise?”
There are two leading hypotheses. One is that the sun boiled Venus to death. The other is that volcanoes did.
Further reading: Venus could have been a paradise, but turned into hell. Earthlings, pay attention.
Where the hell did the moon come from?
Before the moon landed, scientists thought they knew how the moon was formed. The prevailing theory was that it formed much like the planets did: pieces of material left over from the formation of the sun clumped together. But then Apollo astronauts brought samples back from the moon’s surface, and these rocks told a completely different story.
“Geologists had found that the moon was covered by a special type of rock called anorthosite,” Inexplicable senior producer Meradith Hoddinott explains about the show. “Sparkling, bright and reflective, this is the rock that makes the moon shine white in the night sky. And at that time, it was thought, this rock could only be formed in a very specific way. Magma.”
But magma means that the moon must have formed in a kind of epic catastrophe. “Something that flowed so much energy into the moon that it literally melted,” says Hoddinott. Researchers are not entirely sure how it all played out. But each scenario is a film story of burning apocalyptic proportions.
Further reading: How Apollo lunar rocks reveal the epic history of the cosmos
Is there anything living in human feces on the moon?
During the Apollo lunar missions, astronauts went to the moon, and to save weight to return to Earth, they dumped their waste behind. Across all Apollo missions, astronauts went 96 bags of human waste on the moon, and they ask a fascinating astrobiological question.
Human waste – and especially feces – abounds in microbial life. With the Apollo moon landings, we took microbial life on Earth to the most extreme environment it has ever been in. Which means that the waste on the moon represents a natural, but unintentional, experiment.
The question the experiment could answer: How resistant is life in the face of the moon’s brutal environment? And for that matter, if microbes can survive on the moon, they can survive interplanetary or interstellar travel? If they can survive, then it may be possible that life could spread from planet to planet, ride on the backs of asteroids or other such space debris.
Further reading: Apollo astronauts left poop on the moon. We have to go back for that shit.
Was there an advanced civilization on earth before humans?
Many scientists have long wondered: Is there intelligent life in space? But climate scientist Gavin Schmidt and astrophysicist Adam Frank have another question: Was there intelligent life in the deep parts of Earth’s history? Could we find evidence of an advanced non-human civilization that lived perhaps hundreds of millions of years ago, buried in the earth’s crust?
This is not strictly a “solar system” mystery, but it is cosmic in scope. At the heart of it, Schmidt and Frank ask: How likely is it that an intelligent life form on any planet – here or in the deepest parts of space – leaves a mark, a sign that they existed? And for that matter: Hundreds of millions of years from now, will any alien explorers landing on Earth be able to find traces of humans if we are long, long gone?
Further reading: The Silurian hypothesis: would it be possible to detect an industrial civilization in the geological survey?
Can we push an asteroid out of a collision course with Earth?
Many disasters – volcanic eruptions, earthquakes, hurricanes, tornadoes – are inevitable. Researchers are talking about when, not whether they want to strike. Although people make some disasters worse, natural disasters have happened since long before we were here. They are a fact of life on earth. But one type of disaster does not have to be inevitable: a collision between an asteroid or comet and Earth.
The problem is: we’ve never tried to divert an asteroid, and we do not know if a plan to do so would work.
To answer this question, NASA last year launched the Double Asteroid Redirection Test (DART), which is a car-sized box equipped with solar panels. It is currently on its way to a 160 meter long asteroid called Dimorphos. This fall, DART will crash into Dimorphos at 24,000 kilometers per hour (about 15,000 miles per hour) in search of a big question: Can the collision push the asteroid into a slightly different orbit?
Further reading: The quest to avert an asteroid apocalypse is going surprisingly well
Has there ever been life on Mars?
March today is a desert, devoid of clear signs of life. But over the years, scientists have uncovered evidence of a lost Mars, long ago, which may have looked much more like Earth.
“Mars is a completely different place today than it was 4 billion years ago, but you can see evidence of what it was like,” says NASA astrobiologist Lindsay Hays. “You see things like the remains of a huge river delta, indicating that you not only flowed water, but that you probably had a lot of water flowing over a long period of time that continued to deposit sediments.”
And where there was water, there could have been life. Last year, a new rover landed on Mars, and it’s our best shot to answer the question “was there ever life on Mars?” If the answer is “yes”, it can change our understanding of how ordinary life is in the universe.
The Inexplicable episode on Mars airs June 22nd.
Further reading: NASA’s latest rover is our best chance to find life on Mars so far
Is there a real ninth planet lurking in the dark?
In 2006, the International Astronomical Union voted to change the definition of what constitutes a planet, and Pluto failed to make the cut. There were no longer nine official planets in the solar system, but eight.
But then “we started getting these hints that there really is something else out there – and a real giant planet that we think is still lurking far beyond Neptune and waiting to be found,” says astronomer Mike Brown. Inexplicable. Astronomers have not yet discovered this planet, but they suspect it is there: Other objects far out in the solar system appear to be affected by gravity.
Can these hints lead us to a true, new ninth planet? May be. But it will be difficult to find.
“It’s a bit like taking a small grain of black sand and throwing it on the beach,” Brown said of the search. “It would be a little difficult to find it in the sea of all the others. And that’s the problem with Planet Nine. “
Further reading: The hunt for the planet 9
If you have ideas for topics for future shows, send us an email at email@example.com.