How space can be scarier than you think

SPACE is usually spoken about in hushed tones of wonder and amazement.

The distances, sizes, and beauty of everything involved leaves us somewhat awestruck, even if it paints us as such a small part of the bigger picture.

Sadly, the universe's beauty doesn't keep up with its infinite capacity to end us.

Even empty space, alone, with nothing in it, is fatal to we who gaze at the stars.

As a demonstration of the raw, unforgiving, and darkly hilarious power the universe wields, here are five ways the cosmos could be a danger to Earth.

1. Deep Impact

Dinosaur fossils are the universe's way of reminding us that our planet is literally built to attract kilometre-wide rocks to come and ruin our species entirely.

A 4m rock hits our atmosphere with the same energy as a small nuclear weapon, around 4 kilotons.

While rocks smaller than 100m don't usually make it to the ground, an 89m meteor will get to 500m above the surface and detonate with more force than the second largest nuke ever tested. Fortunately these only come around once every 3300 years.

NASA

Were a 100m meteor to hit the ground, you could expect a blast roughly the size of the Tsar Bomb - the 50 megaton horseman of the Apocalypse which leveled everything within 55km and smashed windows 900 km away.

The meteor that (may or may not have) caused the mass extinction event at the end of Cretaceous (bye-bye Dinosaurs) was ten to fifteen kilometres wide and hit with a force 1 billion times that of the bombs aimed at Nagasaki and Hiroshima.

But we're clever, some of us might even survive that, what about the next one ...

2. Supernova

It's a little known fact that you and I were made in a supernova. Not born there, but the heavier elements required for our bodies could only have been created when a star goes supernova.

There are a handful of possible causes [http://en.wikipedia.org/wiki/Supernova], but the common upshot of a star going supernova is that it explodes - hard - with so much force that giant waves of star would be blown through Earth at 10% the speed of light.

SN 1994D (bright spot on the lower left), a type Ia supernova in the NGC 4526 galaxy.
SN 1994D (bright spot on the lower left), a type Ia supernova in the NGC 4526 galaxy. NASA/ESA, The Hubble Key Project Team and The High-Z Supernova Search Team

Supernova are so bright they'll outshine their parent galaxy, but even that luminosity is only a fraction of the energy they release. Even a Supernova 8000 light-years away can wreak havoc on our atmosphere.

Fortunately our own sun will die a slow death, and the closest supernova candidate, IK Pegasi (HR 8210), 150 light-years away, isn't expected to detonate for several million years. Even then it won't be a big one.

So the explosion of Earth in a stellar detonation isn't hugely likely, but going grenade isn't the only way a star can die ...

3. Black holes

We hear about these a lot, but for those playing at home, a black hole is caused when a stellar body, usually a star, collapses under its own gravity. The gravity keeps crushing and crushing until the density is at a point where the speed of light isn't fast enough to get you away from it.

That sounds bad enough, but at least the previous catastrophes let your atoms float on to contribute to some future part of the universe.

This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies.
This artist's concept illustrates a supermassive black hole with millions to billions times the mass of our sun. Supermassive black holes are enormously dense objects buried at the hearts of galaxies. NASA/JPL-Caltech

Not black holes. You'll be stretched out, spaghettified, and then - nobody really knows. The laws of physics are somewhat murky at the centre of a black hole (singularity) but it's unlikely you, your spaceship, your planet, or your solar system could survive the tidal forces and gravity.

While smaller black holes can be the most violent, Supermassive black holes are thought to lurk at the centre of galaxies and are thousands to billions of times the mass of our sun.

While black holes have a note of finality, they're not quite the most dramatic way to go ...

4. Starquake

Let me set the scene. Going from a 5.0 to a 6.0 on the Richter Scale is a jump from 2 Terajoules of energy to 63 Terrajoules. Go from 6.0 to 7.0 and the jump in energy expands to 2 Petajoules.

The gap between magnitudes increases each time (logarithmic). So when a 9.0 earthquake hit Japan in 2011, entire regions were flattened. A 9.5 quake in Chile in 1960 was the largest earthquake in recorded history.

A magnitude 13 earthquake would be the same as the aforementioned meteor impact that probably killed the dinosaurs.

An artists's concept of the 2004 occurence in which a neutron star underwent a
An artists's concept of the 2004 occurence in which a neutron star underwent a "star quake", causing it to flare brightly, temporarily blinding all x-ray satellites in orbit.

So consider that huge upscaling when thinking about a neutron star generating a magnitude 32 'starquake' across its surface.

If that were to happen within ten light-years of earth, we'd all enjoy a mass-extinction event.

The mental image is staggering - the surface of a star so dense it is almost one giant atom made of neutrons suddenly shifting and grinding so hard it could kill us from a dozen stars away.

But we'd know if that were coming at least ...

5. Gamma-ray burst

When a fast-spinning massive star collapses during a supernova or hypernova, it can eject a narrow beam of radiation called a gamma-ray burst (GRR) which in seconds will put out as much power as our sun will in its billions-of-years lifetime.

Satellites pick up a GRB event roughly once a day, but fortunately they're usually in galaxies hundreds of millions of light-years away. What would happen if one of these star-sized ray guns were to hit us from within our own galaxy?

Artist's illustration of one model of the bright gamma-ray burst GRB 080319B. The explosion is highly beamed into two bipolar jets, with a narrow inner jet surrounded by a wider outer jet.
Artist's illustration of one model of the bright gamma-ray burst GRB 080319B. The explosion is highly beamed into two bipolar jets, with a narrow inner jet surrounded by a wider outer jet. NASA/Swift/Mary Pat Hrybyk-Keith and John Jones

The short answer is, everything on the near-side of the planet would be wiped out.

The long answer is, anything left including humans would have to deal with no longer having an ozone layer.

Even a short GRB would cause an extinction-level event. We're fairly sure one already has at least once in Earth's history with the Ordovician-Silurian extinction events.

What makes this the bigger threat than a starquake or supernova or black hole is that, while unlikely, this could happen.

AMAZING SPACE

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