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Wednesday, 15 February 2017

The Universe in 101 words: The 'Oh-My-God' Particle

It's possible the particle came from the kind of exotic objects that lurk in vast nebula, like this one.

Can anything made of matter reach lightspeed? The 'oh-my-god' particle came damn close: A subatomic particle that struck Utah in 1991, it stunned the physicists at the University of Utah's cosmic ray observatory - it was travelling so close to lightspeed that light would only have gained a 1 cm lead in 200,000 years. 

No-one knows how it got such incredible speed, but it must have had a strange trip: So close to lightspeed time slows to a crawl and distances contract - the Universe would seem squashed along the direction of travel, and its whole history would pass in days. 

Above: Such energetic particles can cause cancer in astronauts.

Monday, 13 February 2017

6 Of the best images of Mars

Above: Frost on the Martian desert. While the most recent missions hint at rare flows of briny Martian water, we've known since the Viking landers that ice is common enough on the red planet - here Viking 2 captured the early morning frost settling on the soil.

Above: At 27000 meters high  Olympus Mons is the biggest volcano,  and the biggest mountain,  in the solar system.  It's so big that the peak sticks out of the atmosphere and into space -  and, if you were to stand on it's slopes, you wouldn't be able to tell where the real horizon was and what was merely the curve of the mountain.

Above: The two teeny Martian moons whizz across the sky, one in the same direction as the Sun and one against it.  They are so small they're hard to tell from asteroids,  but they give Mars a phenomena we never see on Earth: Moon on moon eclipses

Above: Mars wears the Valles Marineris is a canyon system like a pirate's scar. It's so big it could would swallow Earth's grand canyon like a tic tac: 7Km deep and running for 4000  km the canyon is part giant rift valley,  and part carved by ancient running water,  deep in the Martian past

Above: The Sun sets on Mars. The sunsets on Mars are blue,  thanks to the way the dust in the ochre sky scatters light.  It's beautiful, but beware -  in the Martian night temperatures can easily reach a hundred degrees below freezing.

Above: A massive Martian dust devil, as seen from space. Dust devils on Mars can be hundreds of meters wide and thousands of meters tall. Some even travel in clusters,  wandering the landscape like nomads. Of all Martian weather they are probably the most spectacular and, even though the thin martian wind doesn't carry much force, being caught in one would mean being pelted with flying sand

Wednesday, 8 February 2017

The Universe in 101 words: Is it all a hologram?

Do physicists watch the Matrix too much? That‘s the first thing I think when I hear theories about the Universe being a huge 'hologram'. 

And, knowing my fellow physicists... yes. Yes they do.

But give them a chance: What they mean is that holograms are 2D surfaces containing 3D information, and our Universe might be 2D with the data for our third dimension stored on it. If that's so we’re part of the 3D information trapped on its surface... So how could we know? 

Well University of Southampton physicists may have found the signatures of a hologram in the cosmic microwave background...

Monday, 6 February 2017

Could we come from space?

Hold on there with the tinfoil hats - I’m not about to start talking about how I was kidnapped and probed back in '01*.

Seriously, who travels thousands of lightyears just to stick things up peoples bums? Who does that?!

What I’m talking about is (slightly) less crazy: Naturally occurring space travel. Most of humankind's great inventions have been done first by mother nature, so why should space travel be any different? 

Well… actually, because Earth’s gravity is strong, and it’s atmosphere deep. Only the most violent natural events – massive asteroid strikes – could throw something hard enough to overcome those and reach space. Still… Earth’s history is incredibly long, and filled with such impacts. Could it have happened? 


First a little background: Theories suggesting that Earth life might have naturally migrated to other worlds, or extra terrestrial life might have naturally migrated here, fall under the umbrella term ‘panspermia’. There're a lot of such theories and, yes, many of them belong firmly in the box marked ‘any advocate of this probably wears a tinfoil hat and talks about how he was kidnapped and probed in ‘01’

But others are considered sound science. The least controversial comes from the observation that asteroids and comets, which occasionally hit planets, carry in them some surprisingly (chemically) evolved compounds - exactly the kinds of chemistry we'd expect to see immediately prior to the start of life. Some of these chemical compounds can even form cell-like structures when exposed to water. So it seems quite un-tin-foil-hatish to suggest that asteroids and comets could have brought the chemical ingredients of life to Earth, and to other planets. 

Which, in a roundabout way, gave us this picture....

Another variant of the idea is litho-panspermia, the idea I alluded to earlier: Major asteroid impacts on early Earth and other planets could have splatted large amounts of rocky debris into space, with some of it eventually wandering far enough to fall on other worlds as meteorites. Simulations have shown that the interiors of rocks blown into space this way can stay fairly un-damaged by the forces of the blast - enough for microbes living in pores of the rock to survive the launch and go into hibernation without dying. Then, when one of those rocks eventually drops onto another planet…. 

We know that rocks can travel between planets this way: We’ve found meteorites that were definitely once rocks on the surface of Mars, or the Moon. They’ve told us things about the history of Mars and the Moon that even space probes couldn’t. Some carry evidence of ancient habitable conditions on Mars. 

The journey can be done the other way too: The surface of the Moon is estimated to contain around 200 kg of Earth rocks per square kilometer, blasted free from Earth during various asteroid impacts. The surface of Mars is also thought to hold massive numbers of Earth rocks, scattered across it's surface.

If you can spot one I'll buy you a beer. All the scientists will buy you a beer, for the rest of your life - that's how important it would be. well? Go on, there's a lifetime supply of beer to be had...
Tests and simulations suggest that a micro-organism in hibernation could survive the ‘launch’, and the landing. So it does seem possible that a piece of stone from Earth, thrown onto a course that took it to a nearby world, could transport viable microbes (if the trip was relatively quick – space radiation can damage even a microbe inside a rock several meters across). 

Today there’s a fairly obvious problem with this idea: There are no habitable planets for a wandering space rock from Earth to land on. But 3.5 billion years ago the story was different: A whole host of worlds that are dead today are thought to have hosted habitable environments – we know this from studying rocks from those worlds that made the reverse trip - to Earth! To add fuel to our tin foil hat wearing fire, the rate of asteroid strikes was much higher billions of years ago, allowing many more ‘launch opportunities’ than we see today. 

No–one can say if Earth life has ever made that trip, or if alien life from one of those worlds might have ever landed here. But, if we ever do find microbial life on nearby worlds, we should be cautious before we get too excited – it might not be truly alien, just a long lost cousin… 

*It wasn’t aliens, I just hung around with the wrong crowd. I don’t like to talk about it. 

Wednesday, 1 February 2017

The Universe in 101 words: What is 'space brain'?

Above: Earth - protecting us in more ways than we can see.

Earth’s magnetic field forms a bubble which, aside from helping boy scouts get hopelessly lost with a compass, deflects high energy particles away from our planet.

Those are generally bad for people – they cause cancer, radiation sickness, etc - and they damage brain function (or at least it does in lab rats), so astronauts journeying beyond Earth’s magnetic field could expect steadily worsening depression, anxiety, and memory loss

Since insane, cancer ridden astronauts make for bad press NASA are developing shielding against the particles – although matching the power of Earth’s magnetic field will tough. 

Above: The view from a SpaceX launcher, as it leaves Earth behind.

Monday, 30 January 2017

The Universe in 101 words: Where's the oldest water?

Sea water is old – it arrived as part of the planetesimals that formed the Earth.

But it isn’t the oldest water there is.

In 1998 a meteorite landed in Texas which was once part of a protoplanet - one warm enough for water to flow beneath it’s surface. The water left behind purple salt crystals and, inside them, some of that 5 billion year old water was trapped. When the meteorite was studied, the trapped water was found – and so we know what those alien waters were like, even though they dried up millions of years before Earth was born

Above: The trapped bubbles of water, as imaged by microscope.

Wednesday, 25 January 2017

The Universe in 101 words: Where's the loneliest place in the Universe?

Above: A map of part of the web of galaxies that fills our Universe.

If it seems far to our nearest stellar neighbour, Proxima Centauri, remember: Some star systems wander between galaxies, millions of light years from anything. The loneliest are probably somewhere in the Bootes void, a huge gap in the web of galaxies that spans our universe. 

The sky of a world in such a void would be very strange: Devoid of stars, but against the darkness distant galaxies would be visible. The dim glows of spiral arms and halos would surround their bright, star like, cores, covering as much sky as a full moon, even from millions of light years distance… 

Above: The Amdromeda galaxy, which is 2.5 million light years from Earth - but so big it's faint spiral arms cover as much of our sky as a full Moon.