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Saturday, 14 October 2017

Sound In Space: The Song of Jupiter

Above: The chaotic, Shoggoth inspired, swirl of massive storm systems at Jupiter's pole. Courtesy of NASA/JPL
The JUNO space probe has been wowing the Earth as it returns astounding images of the beautiful and titanic weather systems that shroud Jupiter - but there's another side to the exploration of the King of the Giant Planets: Jupiter's song. 

While space probes cannot pick up the actual sounds in Jupiter's clouds, (due to there being the vacuum of space between them and the planet), their radio antenna can pick up the natural radio transmissions from the giant world's immense magnetic field. 
So, for the full 'Jupiter experiance' try playing the two videos below - one a high def flyby of Jupier's cloud tops and one a recording of its eerie radio song - at the same time....





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Sunday, 1 October 2017

Five of the strangest asteroids and dwarf planets...

Above: Pluto, a world half the size of the US but stranger than anything dreamed up by sci-fi writers.

Most people thinking of space exploration think of the planets - Mars, Venus, even Jupiter and its Moons. But that's missing something - hundreds of somethings in fact: The large asteroids and dwarf planets make up a collection of worlds as varied and compelling as the terrestrial planets. So here are a few of the oddest...

Ceres:
The king of the asteroid belt, Ceres is a dwarf planet nearly a thousand kilometres across. It's also one of the relatively few asteroids to have been visited by a human space craft - in fact the Dawn space probe is still in orbit, surveying this small world. Despite its small size Dawn has shown that there's still recent signs of geologic activity on that 4 billion year old surface, and perhaps even hints of subsurface water.

Above: A simulated flight over Ceres, assembled from data supplied by the Dawn probe.


Vesta:
The first small world visited by the Dawn probe, Vesta proved to be a world with a history of cataclysmic violence. Already suspected to have been a hot, churning, volcanic world in its youth, Dawn found that the tiny world’s entire South Pole had been obliterated, not once but twice, by gigantic asteroid impacts. The largest of these was so huge it left the 'ripples' caused by the shockwave permanently imprinted in the Vestan rock.

 
Above: Dawn's greatest finds at Vesta

Psyche:
Although we've only ever seen this world at a distance, through telescopes, it is due to be visited by a unique space probe (also called 'Psyche') in 2026. Why? Because it's a solid chunk of metal the size of the state of Massachusetts. The only sensible explanation anyone has come up with (so far) is that Psyche was once the core of a planet - a planet that suffered some terrible fate which stripped down to its metal core...

 Above: The bizarre metal asteroid Psyche, and the mission to explore it.

Sedna:
It's unlikely that Sedna, a world 8 billion kilometres from Earth with a year over 11,000 Earth years long, will get a visit from any spacecraft soon. Even so, it's playing a pivotal role in our exploration of the dim outer reaches of our solar system. The dwarf planet's odd shaped orbit could be the result of the gravity of a ninth major planet, far out in space. Or, perhaps even more intriguingly, it could be a sign that Sedna is not really a member of our solar system at all: It could have been a loosely bound dwarf planet of another star, kidnapped by our sun during a rare stellar flyby.

Above: Think you know how far a long way is? Well take a look at the orbit of Sedna...

Pluto:
I take it you've heard of this one? Although the debate still rages in parts as to whether its demotion from planet to dwarf planet was a fair one, I really don't think this immense and incredibly complex ice world cares. From it's weird hundred meter blades of ice, to its nitrogen ice glacier ocean on which mountains float like ice bergs, to the hints that rivers of liquid nitrogen once flowed on its surface and might well still run beneath its subsurface, Pluto has every reason not to give a damn what we teeny humans classify it as. But, thanks to the New Horizons space probe, this beautifully weird world has, been opened up to human eyes...

 
Above: A virtual fly over of Pluto, assembled using data from the New Horizons mission.


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Wednesday, 12 July 2017

Sound in Space: The drumbeats of pulsars

The Allen Antenna array.

The stars are beautiful, or at least very sparkly. But most people will tell you they're not much to listen to - after all, in space no-one can here you scream, so how would you hear the stars? But there are signals out there - radio wavelength signals - that we can listen to with the right equipment.

So, if you wore radio dishes on your ears, what would you hear?*

Not a peaceful sky, or even a snatch of Beethoven. No, you'd hear a Milky Way echoing to the buzzing, humming, and drumming sounds of pulsars. These are incredibly dense objects, forged from the collapsing cores of supernova - and spun up to incredible speeds by them. Never more than twenty kilometres across, a new born pulsar can spin hundreds times a second. They give out intense beams of radiation, including radio waves, so as they spin radio antenna on Earth hear the click of the beam briefly sweeping over us.

There are old, slow ones that drum like a runners footsteps...


... and there are fast young ones that swarm in star clusters like 47 Tucanae, filling the sky with a whine like the universe's most terrifying cloud of mosquitoes...


But a universe full of strange knocking and humming sounds isn't the odd bit. The odd bit is that you can buy an album of music made using them.

*Given my knowledge of fashion this could actually be a thing for all I know



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Friday, 7 July 2017

The Universe in 101 words: Why should we return to Enceladus?

Above: The dwarf planet Ceres, which is suspected of having once held an underground ocean. Um. It doesn't really turn back and forth in that way
Our solar system is, well, awash with ocean worlds. And, thanks to the Cassini mission, we've gotten to know one really well: Enceladus, 500km wide moon of Saturn.

So what's it like?

Dark - the ocean's covered in 20Km of ice - but maybe not totally black: There's volcanic activity on the ocean floor, like the white smoker vents of earth, so there'd be the dim  glow of volcanism. More importantly the salty, alkaline, water contains organic chemicals and hydrogen - food for possible micro-life.

Cassini's mission is nearly over - but it's now hard to imagine us not returning to Enceladus....

Tuesday, 4 July 2017

Sound in Space: The noise of interstellar space



It may be true that in space no-one can hear you scream, but you can hear some far stranger things out there.

The recording above was taken by the Voyager 1space probe, as it left our solar system - it's of waves with the same frequency as sound, but it's not sound as we know it. Where regular sound is a vibration in a gas, solid or liquid, these sounds are vibrations in the ultra thin soup of ions, called plasma, that fills space. Far too faint for any human sense to detect, Voyager had been listening to vibrations like these for decades. But this set was different - their pitch was suddenly a lot higher. That meant the density of the plasma they travelled through had changed dramatically in a short space of time - one of the markers for the boundary with interstellar space.

So the weird little vibrations are literally the sound of Voyager going where no-one had been before...


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Friday, 30 June 2017

The Universe on 101 words: What's the fastest star?

Above: A hypervelocity star creates a huge bow wave of dust and gas as it ploughs through the Orion nebula.
What phrase describes the night sky? Not 'full of speed demons', unless you've ingested something hallucinogenic. But stars only appear unmoving because they're incredibly distant - most are actually travelling at hundreds of kilometres a second. And some,  called hypervelocity stars, are travelling at thousands.

The record holder for straight line speed? The star US 708, at 1200 kilometres per second.

What could throw a whole star so hard? 

Some were blasted up to speed by supernova. Others got accelerated by the gigantic black hole in centre of our galaxy

And some we can't explain - even after years studying them...



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Above: The Milky Way. Full of the stellar equivalent of angry teenage boy racers. Comforting thought,hey?

Friday, 23 June 2017

The best images of planets beyond our solar system

The last ten years have been an amazing time: Growing up the idea of finding planets around other stars was mentioned to me in textbooks... at the very end, usually in the same very short chapter that mentioned ideas like space hotels, finding intelligent aliens, or building colonies on Mars.

Above: A private SpaceX space capsule on Mars. Good luck borrowing sugar from the neighbours guys...
  And, now, we have found thousands of planets around other stars. Many of them are far stranger than my textbooks expected, which assumed we'd find that solar systems similar to our own. The reality has been that solar systems come in all kinds of exotic configurations. Those books thought we'd be finding these worlds with direct imaging, using massive telescopes - by and large we haven't: Almost all of them were found by indirect means, like watching for stars wobbling, planets occulting the stars they orbit, or gravitational lensing of the light from background stars*.

But not quite all: Although it's still very hard to do, some exo planets have been photographed directly by very, very large telescopes just like my textbooks expected. Below are some of the best. Think of them as a teaser for the future: These fuzzy points of light are what the next generation of telescopes will be improving on - and they're also actually images of something I thought I might never get to see. 

Which is pretty damn cool...


1: Formalhuat b


NASA Hubble Space Telescope has revealed this: A gigantic disk of debris surrounding the nearby star Fomalhaut. Circling it is a planet on an unusual elliptical orbit that carries it on a path straight through the debris - probably not great news for the planet itself. The planet, called Fomalhaut b, swings as close to its star as 4.6 billion miles, and the outermost point of its orbit is 27 billion miles away. 
"We are shocked. This is not what we expected," said Paul Kalas of the University of California and the SETI Institute. They suspect that this is evidence of another planet gravitationally 'interacting' with Fomalhaut b. That's scientist code for 'having a huge fight which Formalhaut b lost', hence why this planet is on an orbit that exiles it to the far end of its solar system. .  


2: Beta Pictoris B


This image was taken by the Gemini Planet Imager (GPI) , and it shows a planet, beta Pictoris b, orbiting the star Beta Pictoris. Beta Pictoris b is a new born giant planet -- several times larger than Jupiter and just ten million years old. Its so young it's still glowing in infrared light from the heat released in its formation. The bright star Beta Pictoris is hidden behind a mask in the center of the image - the large blank circle.


3: ROXs428b


This possibly-planet has an estimated mass between 6 and 15 Jupiter masses. Exactly how much it weighs is important, because things lighter than 13 Jupiter masses can't generate enough pressure in their cores for nuclear fusion, and are definitely planets. Objects heavier than that can generate enough pressure in their cores for a brief burst of deuterium fusion (the weediest kind - true stars use hydrogen fusion) in their youth, which makes them 'brown dwarf' sub stars. Whichever side of that division it's on it's a bigger object than Jupiter, and like Beta Pictoris b it's young enough to still glow with heat from its birth.




4: HR8799


An image of an exoplanet is rare, but videos of them are like diamond dust. The star HR 8799 is even rarer: It has not one but four planets big enough to be imaged from earth, andhere they are gently orbiting their primary. This time lapse video took seven years to make, with each frame being shot using at the W.M. Keck observatory in Hawaii. The black circle in the middle blocks the blinding light of the star, and thus make the planets visible.


5: GJ504 b

 


Several times the mass of Jupiter and similar in size, this new world, dubbed GJ 504b (what's with all the dull-ass names I wonder), is the lowest-mass planet ever detected around a star like the sun using direct imaging techniques. "If we could travel to this giant planet, we would see a world still glowing from the heat of its formation with a colour reminiscent of a dark cherry blossom, a dull magenta," said Michael McElwain, a member of the discovery team at NASA's Goddard Space Flight Center in Greenbelt, Md. "Our near-infrared camera reveals that its colour is much more blue than other imaged planets, which may indicate that its atmosphere has fewer clouds."






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