# Can an Earth-like planet survive if our Sun went Supernova?

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First, I would like to point out, yes, our sun does not have enough mass to be a candidate for Supernova, this is a scenario were our sun is though, and after the various life cycle stages of the sun and whether or not life managed to survive or not on the planet, The Sun goes of as a Supernova, it is 1 AU from an Earth-like planet, or equivalent to 1 AU from a massive star, would the planet still be standing or would it be obliterated from the face of the Galaxy?

Here are some of the links that I have been looking through but could not find an answer for:

One way of estimating this is to look at how much energy could be received by the planet. At distance $$d$$ it takes up $$r^2/4 d^2$$ of the sky as seen by the supernova. So for a $$10^{44}$$ J blast that is about $$4.5444 imes 10^{34}$$ J.

The gravitational binding energy of Earth is about $$2 imes 10^{32}$$ J. So we have about 227 times as much energy as is needed to separate all pieces of the planet to infinity. It is also a few thousand times the energy needed to heat up an Earth-mass of iron from 0K to vaporisation. So, yes, it looks like it could well obliterate the planet.

Whether it actually does so is a complex question of how protected the evaporating planet is by its plasma sheath during the explosion. Given that actual terrestrial exoplanets in close orbits at 2000K may lose an Earth mass per gigayear it looks plausible that at least slower scenarios can vaporise planets.

If the sun were a much larger and more massive star of the kind that supernovae are made of, the Earth at 1AU would be in pretty poor shape anyway, a scorched cinder. Life would never even get started, never mind survive. In the supernova explosion the surface of the Earth would be blasted away and whatever was left propelled at great speed out of the solar system, and pretty much obliterated from the galaxy. The actual fate of the Earth is more interesting, as it is really going to happen in about 5 billion years time. When the sun becomes a red giant, the Earth will be scorched to a cinder and all life on Earth will cease. After expelling some mass, the sun will finally become a white dwarf about the size of Earth.

## This Is What Would Happen if the Sun Suddenly Exploded

The sun is a star, and when a star explodes it’s called a supernova. These types of explosions are very bright and very powerful. They release lots of dust into space, which is used to make more stars and planets. Our solar system was made using stuff from these explosions. Even humans are made of star stuff!

If the sun suddenly exploded like this, the whole solar system would be destroyed. You don’t have to worry though — only stars 10 times the size of our sun, or bigger, can explode like this. Our sun will end its life in a different way.

A supernova is like bursting a balloon. But when our sun dies, it will happen slowly, like when you gradually let the air out of a balloon.

## If The Sun Went Out, How Long Could Life On Earth Survive?

Don't worry, you'll have time to post your goodbye selfies to Facebook.

NASA/Solar Dynamics Observatory

If you put a steamy cup of coffee in the refrigerator, it wouldn’t immediately turn cold. Likewise, if the sun simply “turned off” (which is actually physically impossible), the Earth would stay warm—at least compared with the space surrounding it—for a few million years. But we surface dwellers would feel the chill much sooner than that.

Within a week, the average global surface temperature would drop below 0°F. In a year, it would dip to –100°. The top layers of the oceans would freeze over, but in an apocalyptic irony, that ice would insulate the deep water below and prevent the oceans from freezing solid for hundreds of thousands of years. Millions of years after that, our planet would reach a stable –400°, the temperature at which the heat radiating from the planet’s core would equal the heat that the Earth radiates into space, explains David Stevenson, a professor of planetary science at the California Institute of Technology.

Although some microorganisms living in the Earth’s crust would survive, the majority of life would enjoy only a brief post-sun existence. Photosynthesis would halt immediately, and most plants would die in a few weeks. Large trees, however, could survive for several decades, thanks to slow metabolism and substantial sugar stores. With the food chain’s bottom tier knocked out, most animals would die off quickly, but scavengers picking over the dead remains could last until the cold killed them.

Humans could live in submarines in the deepest and warmest parts of the ocean, but a more attractive option might be nuclear- or geothermal-powered habitats. One good place to camp out: Iceland. The island nation already heats 87 percent of its homes using geothermal energy, and, says astronomy professor Eric Blackman of the University of Rochester, people could continue harnessing volcanic heat for hundreds of years.

Of course, the sun doesn’t merely heat the Earth it also keeps the planet in orbit. If its mass suddenly disappeared (this is equally impossible, by the way), the planet would fly off, like a ball swung on a string and suddenly let go.

This article originally appeared in the November 2008 issue of Popular Science_ magazine.—Eds._

Our solar system was formed from gas and dust that includes remnants from a supernova explosion. We know this because we have heavy metals. If we knew more about exactly how they are formed in a supernova, we'd be able to date the one that formed our heavy metals. For example, we know the relative proportions of U-235 and U-238 on Earth rather accurately. That proportion is slowly changing because they are both radioactive and have different half-lives. If we knew the proportions in which they are formed in a supernova, it would be easy to calculate how long ago the supernova happened.

If your planet formed fairly quickly after your supernova, and developed life quite quickly, it's possible to have a life-bearing planet with a high abundance of heavy metals.

## Can an Earth-like planet survive if our Sun went Supernova? - Astronomy

What would happen to life on Earth if the Sun were to burn out how long would we be able to survive?

The Earth's atmosphere has some capacity to hold in heat but not much of one. A relatively simple calculation would show that the Earth's surface temperature would drop by a factor of two about every two months if the Sun were shut off. The current mean temperature of the Earth's surface is about 300 Kelvin (K). This means in two months the temperature would drop to 150K, and 75K in four months. To compare, the freezing point of water is 273K. So basically it'd get too cold for us humans within just a few weeks. Some bacteria seem to be capable of surviving at extremely cold temperatures in space, so there would probably still be some limited bacterial life left on Earth. But anything else would die pretty quickly (even the rats :).

We could probably survive if we went deep underground where the Earth's internal heat is higher or if we built totally isolated habitation domes, but at the moment I don't think we're capable of something like that on any appreciable scales.

#### Marko Krco

Marko has worked in many fields of astronomy and physics including planetary astronomy, high energy astrophysics, quantum information theory, and supernova collapse simulations. Currently he studies the dark nebulae which form stars.

## Can an Earth-like planet survive if our Sun went Supernova? - Astronomy

In the world of exoplanets, Earth-like planets are what everyone’s most excited over. And for good reason. It sure would be great if we could get a close look at one, don’t you think?

Wouldn't it be great if there were an Earth-sized planet nearby right in our own solar system that we could explore with spacecraft now??

&mdash David Grinspoon (@DrFunkySpoon) February 23, 2017

I mean, we all grew up watching things like Star Trek which, obviously, is full of Earth like planets. Many of which look suspiciously like Southern California. Unfortunately, the chances of an actual exoplanet being like that are really quite unlikely (albeit impossible to predict), no matter how much you might want to battle a giant lizard. The thing is, going by the definitions the exoplanet hunters use, there’s an awfully convenient Earth-like planet right nearby. In fact, it’s actually the closest planet to Earth. Its name is Venus.

It feels a bit like we, as a species, haven’t quite forgiven Venus for not being the idyllic paradise planet that the sci-fi writers used to love telling us about. Or at least for not being a swampy dinosaurland.

No, sadly everything that we’ve discovered about Venus seems to be given by people as reasons not to go there. Just imagine if everything about you was considered a good reason not to visit? Besides, while exploring Venus is admittedly not as easy as exploring Mars, there aren’t any difficulties which are insurmountable.

Human technology has progressed greatly since the old Soviet Venera landers. Moreover, we now know what kind of conditions we’ll need our technology to stand up to, if we try sending robots to Venus.

Sulfuric acid? No problem. We can use high grade ceramics and fluorinated polymers which are resistant to acid attack.

High pressure? Venus has a surface pressure of about 9.1 megapascals, and we have deep sea submersibles which can comfortably survive ten times that much.

Furnace-like temperatures? Sure, most human made electronics use semiconductors which can’t function above 250°C, but we know how to construct electronics that can.

Seriously though, Venus is tragically underexplored. It’s actually the most visited other planet in the Solar System, but sadly, that’s purely because it’s a convenient way to get a gravitational slingshot before continuing to go somewhere else. NASA doesn’t seem to want to touch Venus with a proverbial barge pole, having not sent any spacecraft there since Magellan in 1989. Since then, there have only been two craft sent specifically to study Venus – ESA’s Venus Express, and JAXA’s Akatsuki. Though ISRO are considering sending a craft that way.

It’s a pity, really. Because while exoplanet astronomers are busily finding Earth-like planets, our only real criteria defining them as “Earth-like” are that they are of a similar mass and equilibrium temperature ★ to Earth. By that definition, Venus is most definitely an Earth-like planet. Which means we have two Earth-like planets which we can study up close, characterise, try to understand, and ultimately use in making predictions about exoplanets. And right now, we have no way of knowing if the planets we find elsewhere are going to be more like Earth, more like Venus, or altogether different. For all we know, the planets we’re discovering may actually be Venus-like, with genuinely Earth-like planets being an oddity.

With all this in mind, you’d think it might be a good idea to spend some time studying the only other Earth-like planet we’ll be able to actually visit in the near future.

It’s worth pointing out that by equilibrium temperature, I mean the temperature predicted for an object without an atmosphere. Equilibrium temperatures of Venus and Earth are roughly 260 K (-13°C) and 255 K (-18°C) respectively, which really does go to show what a huge difference a planet’s atmosphere can make.

## Planet Hunters: On a quest for astronomy's holy grail

Sara Seager hopes to complete the Copernican Revolution by locating a true Earth analog beyond our solar system.

It's fitting that Sara Seager is fascinated by stories of explorers visiting uncharted places. From her groundbreaking work on the detection of exoplanet atmospheres to her innovative theories about life on other worlds, Seager has been a pioneer in the vast and unknown world of exoplanets.

Now, like an astronomical Indiana Jones, she's on a quest after the field's holy grail - another Earth-like planet.

In addition to her role as a professor of planetary science and physics at MIT, Seager is also a part of numerous planet hunting committees and projects. She's served on NASA's Exoplanet Task Force and on the Terrestrial Planet Finder science teams. She is currently a participating scientist on the Kepler planet-hunting mission, a co-investigator on the planet-studying EPOXI mission, and is the science team lead on the eXtrasolar Planet Characterizer (XPC) concept study.

PlanetQuest caught up with Seager recently to find out what life is like on astronomy's cutting edge.

PlanetQuest: Do you think that an Earth-like planet will be discovered in your lifetime?

Sara Seager: I like to live in the future, and I'm getting older, so I'm determined to find another Earth-like planet in my lifetime. The super-Earths are interesting, but the difference between them and a real Earth is like the difference between finding your long-lost twin and finding a very, very distant cousin that you have nothing in common with. So I'm working on a concept study for a mission that will look at the very brightest stars in the sky, because those are the only ones that are bright enough for follow-up observations to detect the atmosphere of an Earth-like planet.

Seager is one of the scientists involved with the Kepler planet-hunting mission, scheduled to be launched in 2009.

My idea involves small telescopes in space, each looking at a bright star for signs of a Earth-like planet going in front of the star as seen from Earth, which is called "transiting". I'm convinced that it's going to be successful and that we'll be able to complete the Copernican Revolution.

PQ: You're well-known in scientific circles these days, but how did you get your start in exoplanets?

SS: Well, I was looking for something different to do for my PhD thesis back in 1996, so I decided to write about the properties of hot exoplanet atmospheres - this was one year after the first exoplanets around sun-like stars were discovered in 1995, and no one else had written about this topic. Later, I was the first to propose the detection of exoplanet atmospheres by observing as they transited their host stars. The methods I proposed back then are being used on missions like the Spitzer Space Telescope and the Hubble Space Telescope to detect the composition of exoplanet atmospheres - and they're finding the atoms and molecules that I predicted would be there.

PQ: That's an amazing achievement. What does your work involve these days?

SS: I'm currently a professor of planetary science and physics at MIT - I create models of planet interiors and atmospheres to understand observations of exoplanets. I also study what atmospheres might look like on "Earth cousins" - planets like ours that could have all different kinds of atmospheres, where life could have adapted differently to the conditions on that planet. I'm also working on how we can apply the methods we use to look at the atmospheres of giant planets to smaller, "super-Earth" size planets using the future James Webb Space Telescope.

PQ: What keeps you interested in studying exoplanets?

SS: For me, the hook is the idea of an Earth-like planet, knowing that there's an Earth analog out there. The Kepler mission will be able to tell us if planets like our own orbiting other stars are common, something that will really change the way we look at things. I like to think of finding a true Earth analog as the completion of the Copernican Revolution - Copernicus started a new paradigm when he said that the Earth was not the center of the universe. If we can identify another Earth-like planet, it comes full circle, from thinking that everything revolves around our planet to knowing that there are lots of other Earths out there.

PQ: What's been the most surprising thing you've learned during the course of your career?

Seager is the science team lead for the eXtrasolar Planet Characterizer, a future NASA exoplanet mission concept.

SS: I can think of two surprises: one, any kind of planet is out there, at every semi-major axis. The process of planet formation is random and we've seen planet masses and orbits we never thought could exist. And the second surprise is about the physical characteristics of some planets. For example, how did the "hot Jupiters" get so huge and close to their host stars? Some are bigger than we thought planets could be, too big for us to understand why right now.

PQ: What Earth-bound hobbies do you pursue when you aren't planet hunting?

SS: Well, I have two little kids, so I don't have that much spare time anymore, but I really like canoeing in the Arctic the northern environment really forces you to push yourself. I like to read, too, books and magazines. My favorite book is "Sleeping Island: The Story of One Man's Travels in the Great Barren Lands of the Canadian North." It's about a Midwest schoolteacher around the 1930s who, every summer, went canoeing in parts of northern Canada that hadn't been mapped yet, just exploring and meeting natives. I like the idea of modern-day-explorers, that sense of adventure about the unknown.

## Can Life on Earth Escape the Swelling Sun?

Welcome to the last day on Earth. Humanity's descendants have long since died or fled, oceans have long since vaporized, and the life-giving sun has ballooned into a swollen giant filling the sky.

Scientists have debated for years what will happen to our planet when the sun's fusion furnace begins to run out of fuel and swell into a red giant a few billion years from now. The most recent simulations suggest that Earth will end up being swallowed by the dying sun.

The impending doom is more dire than any fictional villain could ever wish upon a world. Yet the planet need not perish if future civilizations can somehow move Earth out beyond the danger zone. Barring that, a clever escape plan might prove useful.

The fate of life on our planet has always depended upon the sun's destiny. Astrophysicists can trace both the sun's past and future based on their understanding of stellar evolution, which comes from observing stars of many types and at different stages of life.

Larger stars typically meet their end in spectacular supernova explosions, and leave behind either neutron stars or black holes. But mid-size stars like the sun experience a more gradual transformation, after they consume the last of their hydrogen fuel and start burning helium.

Helium burning leads to higher core temperatures that would cause the sun to start swelling into a red giant, around 5 billion years from now. Simulations show the sun eventually expanding to around 250 times its current size.

Previous studies showed that expanding sun would engulf Mercury and Venus, while Mars would remain safely out of reach. But Earth remained in a zone of uncertainty because of its location between those planets. A faint chance existed that the sun would lose too much mass before getting too big, and would allow the Earth to escape into a wider orbit as the sun loses its gravitational grip.

Final sunset

Now any hope for Earth's final salvation may have finally died. British astronomers ran a simulation in early 2008 which included the sun's weakened gravitational pull, and the Earth moving outward in response.

"If that were the only effect, the Earth would indeed escape final destruction," said Robert Smith, emeritus reader at the U.K.'s University of Sussex. "However, the tenuous outer atmosphere of the sun extends a long way beyond its visible surface, and it turns out the Earth would actually be orbiting within these very low density outer layers."

That low-density gas would cause enough drag for the Earth to drift inwards, even as tidal forces caused by the Earth's gravity force the nearest side of the sun to bulge outwards. The Earth eventually drifts into the bulge and ends up vaporized, around 7.6 billion years from now.

However, life has even less time than the planet. Most scientists agree that every living thing faces certain extinction 1 billion years from now, when the sun's growing brightness transforms Earth into a global desert. Dropping carbon dioxide levels would starve plants of the ability to conduct photosynthesis, and that would lead to the inevitable death of all living things.

Life after Earth

A long shot exists for life to survive Earth's fate, but it would involve some novel solutions or a serious space colonization effort.

One team at Santa Cruz University in California has proposed capturing a passing asteroid and using its gravitational effects to "nudge" Earth's orbit outward. A continuous asteroid passage every 6,000 years or so could keep Earth at a comfortable distance and give life another 5 billion years on the planet.

People leery of miscalculations with the asteroid solution could also turn to good old fashioned engineering. Humans may find new homes among the asteroid belt, the outer planets, in artificial colonies, or perhaps beyond this star system. "Space is disease and danger wrapped in darkness and silence," complains Dr. Leonard "Bones" McCoy of "Star Trek," but even life aboard a starship would beat species extinction.

"A safer solution may be to build a fleet of interplanetary 'life rafts' that could maneuver themselves always out of reach of the sun, but close enough to use its energy," Smith suggested.

The sun will eventually lose most of its mass as it becomes a white dwarf, and could come to resemble other burnt-out star systems spotted by NASA's Spitzer Space Telescope in a 2009 study. About 1-3 percent of white dwarf stars seem to contain dust and rocky debris, which may represent remnants of rocky planets such as Earth.

By that time, humanity should have either found its new foothold in the universe or long since ceased to exist.

## Apocalypse Never

Given how tiny the chances are of any of these apocalyptic events actually happening, we’re left with the conclusion that tardigrades will survive until the Sun expands about 1 billion years from now. One final, incredibly unlikely possibility is that a passing star could kick a planet out of its orbit . But, even then, volcanic vents that host some tardigrades could potentially provide heat for long enough for the planet to be captured by another star.

There are many events, both astrophysical and local, that could lead to the end of the human race. Life as a whole, however, is incredibly hardy. As we begin our search for life away from Earth, we should expect that if life had ever begun on a planet, some survivors might still be there.