Miranda doesn’t seem like a particularly important moon. It is one of five main satellites orbiting Uranus, travelling along the innermost orbit. It is only 472km in diameter – the smallest of the five major moons. While its surface appears bright, it is in fact second to Ariel in brightness. But Miranda’s unassuming statistics hide a secret. As Voyager 2 passed by Uranus in 1986, it sent back images of an unexpectedly fascinating world.
Nicknamed the ‘Frankenstein moon’, Miranda’s surface merges together like mismatched patchwork. Smooth areas appear alongside heavily cratered ones, and gigantic cliffs give way to deep canyons. However, the most interesting features of this bizarre coalition are the three giant coronae. In this image, the coronae are the “chevron” figures enclosed by concentric lines. Each corona measures around 200km across, and is surrounded by parallel grooves and concentric ridges. They are shaped roughly like trapezoids, giving the impression that Miranda doesn’t quite fit together.
Scientists have proposed several different explanations for Miranda’s curious features. One reason could be that at some point in its history, Miranda was smashed apart in a violent collision, and then gravity caused the fragments to reassemble in a haphazard manner. As rocky material submerged into the newly reformed moon, it produced concentric creases, forming the coronae.
Another possibility suggests that the coronae are impact sites from large meteorites. Miranda is thought to comprise of roughly even amounts of silicate rock and water ice. As these meteorites collided with the moon, they partially melted the ice beneath the crust, causing water to make its way to the surface where it would then refreeze.
However, the most likely scenario to explain Miranda’s exotic features places Uranus squarely into the picture. Given Miranda’s small size, it would have cooled quickly after its formation. This particular structure doesn’t possess the radioactive materials like Earth has to keep its centre hot. Instead, through three-dimensional computer simulations, researchers have demonstrated how Uranus influenced the structure of the moon.
As a result of its gravitational pull, Uranus generated tidal forces, melting the moon from the inside out. In this model, Miranda once had a more oval-shaped orbit. As its proximity to Uranus shifted, the tidal effects constantly stretched and compressed Miranda, enough to generate a considerable amount of heat. This heat was transmitted to the icy mantle so that the crust receded, allowing new material to rise up in its place and form the coronae. As Miranda’s orbit gradually stabilized, the moon stopped producing heat and cooled down into its present form.
Miranda has proved to be a fairly complex world. While we have only seen the southern hemisphere, as Voyager 2 only imaged the one half, we have still been able to view one of the most diverse landscapes ever found on an extra-terrestrial object.
Bizarre Shape of Uranus’ ‘Frankenstein’ Moon Explained.
Sparrow, Giles 2015, ‘The Solar System’, Astronomy in Minutes, Quercus Editions Ltd, London.
As the sun converts hydrogen to helium within its core, there are always different particles released at each stage. These particles are essentially waste so they depart the sun, although at various rates.
During the first phase of fusion two Hydrogen atoms fuse together to make Deuterium, a heavier form of Hydrogen that contains a neutron. Usually Hydrogen contains only 1 proton and NO neutrons. According to our best solar models, the first neutrino produced during the fusion process comes from this step.
Neutrinos are electrically neutral particles with an extremely low mass. They interact with other particles so weakly that they travel through ordinary matter with extraordinary ease. Every second, huge numbers of neutrinos are emitted from the sun, carrying a very small fraction of the energy that is liberated from fusion reactions. They leave the sun and stream right through Earth. In fact, while you are reading this sentence, more than a billion neutrinos will pass through your head. The incredibly low interaction rate of the neutrino makes them difficult to study. I mean, how do we even know they are there??
Experiments to detect them have been running since 1970; the first was set deep in an abandoned gold mine in South Dakota. Being underground helped minimise possible false results by cutting out various other particles.
The neutrino detector consisted of a large tank containing over 600 tonnes of tetrachloroethene – a liquid used in dry cleaning that contains carbon and chlorine. As neutrinos flooded the tank, one would occasionally interact with a chlorine nucleus. Quite surprisingly, every time this interaction happened an argon nucleus was produced. At the end of an 80 day run the contents of the tank were emptied and the argon nuclei counted. What lay before them was an almighty task, as usually only 50 or so argon nuclei were found amongst the approximately 100000000000000000000000000000000 nuclei in the tank (that’s 10 with 31 zeros after it by the way).
The results of this experiment led to what is now known as the solar neutrino problem. The observed neutrinos implied a rate of production that was only one third of that expected. Since this initial experiment in the South Dakota mine, the deficit of solar neutrinos has been confirmed by other experiments that detect neutrinos in a variety of ways.
The answer turned out to be that there are actually three different types of solar neutrino: the electron neutrino, the muon neutrino and the tauon neutrino. Although only the electron neutrino is emitted by the sun, some of them can change type on their journey through space. The South Dakota mine experiment could only detect the electron neutrino type, and the experiments that followed could only detect one type of neutrino at a time. These results made sense as the experiments always detected only one third of the expected neutrinos.
In the late twentieth century solar astronomers finally cracked the issue when they set up an experiment in Canada that could detect all 3 types of neutrino. It used a spherical tank that held 1000 tonnes of “heavy” water surrounded by 9500 photosensitive cells that could detect tiny flashes of light from any particle interactions (the photo shows some technicians cleaning the cells inside such a tank). When they announced their results, it was confirmed that the theory from solar models regarding nuclear reactions, was in fact correct.
MONDAY, JUL 6, 2015
The comet that a spacecraft landed on last year appears to be home to viral particles
Landing a spacecraft on a comet might be an even bigger deal than scientists believed as recently as last year, when the European Space Agency pulled off the magnificent feat in November. According to new reports, the comet in question might be home to alien lifeforms.
Philae, the spacecraft that landed on comet 67P/Churyumov-Gerasimenko, underwent a period of hibernation that ended in June, and has since indicated that there might be “an abundance of alien microbial life” on the comet’s surface,according to The Guardian:
Features of the comet, named 67P/Churyumov-Gerasimenko, such as its organic-rich black crust, are most likely explained by the presence of living organisms beneath an icy surface, the scientists have said.
Rosetta, the European spacecraft orbiting the comet, is also said to have picked up strange clusters of organic material that resemble viral particles. […]
The scientists have carried out computer simulations that suggest microbes could inhabit watery regions of the comet. Organisms containing anti-freeze salts could be active at temperatures as low as -40C, their research shows.
The comet has a black hydrocarbon crust overlaying ice, smooth icy “seas” and flat-bottomed craters containing lakes of re-frozen water overlain with organic debris.
[Astronomer and astrobiologist Chandra] Wickramasinghe said data coming from the comet seems to point to “micro-organisms being involved in the formation of the icy structures, the preponderance of aromatic hydrocarbons, and the very dark surface”.
Scientists also say the comet could provide a similar environment to the otherwise inhospitable areas on Earth occupied by “extremophile” microbes, though it’s unclear what that means for those “terrestrial” organisms.
The Science Report by Stuart Gary
I’ve just written a story for ABC Science about new data showing that the orbits of Pluto’s four smaller moons are thrown out of kilter by the gravitational tug-of-war between Pluto and its largest moon Charon.
The study, published in the journal Nature, provides new insights into how this chaotic system at the solar system’s outer rim formed.
Unlike most planetary systems which consist of a planet orbited by moons, Pluto and its largest moon Charon orbit each other around a common centre of gravity in a binary system.
This binary is in turn is orbited by four smaller moons – Nix, Hydra, Kerebos and Styx.
If you missed my radio report on the story and want to find out more, check out the online version at:
I AM SCREAMING OH MY GOODNESS
OH MY GOD DO YOU GUYS UNDERSTAND HOW AMAZING THIS IS
I HAVE BEEN READING ASTRONOMY BOOKS FOR YEARS AND EVERY TIME THERE’S JUST A PIXELLY BLUR FOR PLUTO
NOT ANYMORE. NEVER AGAIN.
If this is real OH MY GOD PLUTO YOU’RE GORGEOUS!
by Colin Payne, 04/12/15
NASA recently gave a definitive answer to one of the biggest collective questions humanity has ever asked: are Earth’s inhabitants alone in the universe? NASA says the answer is “almost certainly no,” according to Phys.org. And while we could meet our alien neighbors within the next two decades, they may not take the form of what you’re used to seeing in science fiction.
“I believe we are going to have strong indications of life beyond Earth in the next decade and definitive evidence in the next 10 to 20 years, NASA chief scientist for the National Aeronautics and Space Administration, Ellen Stofan said at a public panel in Washington earlier this week. “We know where to look, we know how to look, and in most cases we have the technology.
NASA interim director of heliophysics, Jeffery Newmark added that finding life beyond Earth is “definitely not an if, it’s a when.”
What do they expect to find? Don’t think Klingon or Ewok, think much smaller – microscopically smaller down to the microbe level. “We’re not talking about little green men,” Stofan noted. “We’re talking about little microbes.”
Mars is the main hot spot for NASA’s search for microbial life, as a study that analyzed the atmosphere above Mars’ polar caps suggests half of the planet’s northern hemisphere once had oceans a mile deep that contained water for as long as 1.2 billion years.
However, confirming life on the Red Planet might hinge on the ability to get boots on the ground in the form of field geologists and astrobiologists.
Another key location for life exploration is Jupiter’s moon Ganymede, which a recent study confirmed has a large liquid ocean underneath its icy surface. NASA believes the ocean may be a “habitable zone” where life could exist.
The plan is to drag a boulder into lunar orbit, where astronauts will visit it beginning in 2025.
By: Mike Wall, Space.com Thu, Mar 26, 2015
Via NASA Image of the Day
This is something that broke the heart of any kid who learned how to sing the names of all the planets at school, as it was suddenly made obsolete. Plus Pluto was arguably the cutest planet, but now, we all need to face facts and it seems people are unsure about the real reasons.
So, why is Pluto no longer considered a planet?
1) Peculiar orbital path and distance from the sun: Pluto has a path around the sun that is unlike all the other planets. It is at 17 degrees to the usual orbital plane and is much larger and erratic; sometimes even crossing the orbit of Neptune. It is 5.8 billion kilometres from the Sun, which to put in perspective is around 40 times further than the Earth is from the Sun. Even at it’s closest point it is still billions of kilometres away.
2) It could be in a binary system with Cheron: Although the moon and the Earth sometimes display binary traits; Pluto’s moon Cheron is extremely large comparatively. This results in a skewing of Cheron’s orbit around Pluto, making them both orbit each other simultaneously, as oppose to one orbiting the other.
3) It has not cleared it’s path: Pluto intersects with Neptune’s orbit, whilst also orbiting near objects smaller and even bigger than it. A planet should have strong enough gravity to clear it’s path and should be by far the biggest thing in its area. Putting this into perspective, Earth is 1.7 million times the mass of anything in its neighbourhood, whilst Pluto is only 0.07 times the mass in its neighbourhood.
Why all this rules Pluto out of the planet family?
As Planets are required to clear their paths, they don’t tend to cross each others orbits as their massive gravity’s don’t permit this. Not only that, Pluto’s orbit is so large that it drifts into the Kuiper belt. Inside the Kuiper belt has been dwarf planets even bigger than Pluto; such as Eris. This originally prompted the discussion on what a planet is. Due to the peculiar and erratic orbit, it appears that the Sun’s massive gravity attracted Pluto once upon a time whilst it was travelling past, although didn’t create an orbit as stable as the other planets.
Although we love and miss Pluto, It really should not have been considered a planet in the first place. It seems that it was originally a planet purely because we knew such a tiny amount about our solar system so far away and it was the biggest thing we knew out there. Once we found other space objects similar to Pluto, a definition was required.
Don’t be sad though, Pluto’s consolation prize is that space objects similar to it (such as dwarf planets) are now called “Plutoids”. How sweet.
(Via Youtube 1,2, NASA, HowStuffWorks, Scishow)