Worlds of David Darling

Encyclopedia of Science

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Encyclopedia of Alternative Energy and Sustainable Living

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Latest space and science news

When will we find life out there – or it find us?


If there is life on other worlds in our neck of the Galaxy, we may be just a decade or so away from finding it. More than 1,000 exoplanets are known already, including rocky ones in the habitable zone of their stars. With the launch of the James Webb Space Telescope in 2018 scientists believe they will have the means to detect signs of extraterrestrial life in the atmospheres of extrasolar worlds. And if, by chance, there are industrial alien civilizations within a few hundred light-years of us, this powerful instrument and others may be able to pick out the traces of pollutants. Of course, just as we will soon have this potential, so any intelligent aliens around nearby stars would be able to learn of our presence by similar means.

Read more (Voice of America)

The mysterious crater of Yamal

Yamal crater

This 80-meter wide crater appeared recently in the Yamal peninsula of northern Siberia. What caused it is still unknown, although a few theories are kicking around. It certainly isn't a meteorite or asteroid crater because any kind of high-energy collision wouldn't leave such a hole in the middle. The presence of debris around it also rules out the possibility of it being a sinkhole. One credible explanation is that it formed from the collapse of a soil covered dome of ice called a pingo. More worrying is that it may have resulted from underground methane violently bursting to the surface when the overlying permafrost was weakened due to rising temperatures. If climate change is to blame, this spectacular feature could be the first of many to open up, releasing vast quantities of methane – a potent greenhouse gas– into the atmosphere.

Read more (The Guardian)

The asteroids we need to be most concerned about

Asteroid exploding over Russia

The small asteroid that exploded over Russia last year and caused widespread structural damage served as a wake-up call. Despite all our efforts to keep track of space rocks that might threaten the Earth, some potentially devastating ones can still slip through the net undetected. Astronomers have devised a few different ways to categorize asteroids (and comets) that could pose a threat to us over the next few tens or hundreds of years. One of these measures of 'potentially hazardous objects' is known as the Palermo Technical Impact Hazard Scale. It takes into account both the size of the object and the chance of it hitting us. Topping the Palermo Scale at the moment is an asteroid called 2009 FD. A few asteroids are rated as having a higher chance of hitting us over the next century or so, but 2009 FD comes top of the list because it's also pretty big – almost half a kilometer across – so if it did hit us, depending on where it hit us, it could cause widepread devastation and loss of life.

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The habitable planet that never was

Artist's impression of Gliese 581g and its star

It was the first Earth-like habitable planet to be found: a world about three times as massive as our own, rocky, and right in the middle of its stars habitable zone. For several years, Gliese 581g, discovered in 2010, topped the league table of exoplanets most likely to host life. The trouble is: it doesn't exist. That's the conclusion of a study just published by a research team using two powerful ground-based spectrographs, ESO HARPS and Keck HIRES. Both Gliese 581g and its supposed companion planet 581d are not real worlds at all but features due to magnetic activity on the star as its span around.

Read more (Penn Satte University)

The universe's biggest cold spot may be linked to the biggest cosmic void

cold spot in the cosmic microwave background

Astronomers have known for a few years about a 'cold spot' in the cosmic microwave background – a patch in the sky where the afterglow of the Big Bang is cooler than in other directions. There have been a few theories kicking around to try to explain this curious feature, including the intriguing one that it might be a place where another universe has bumped into ours. But perhaps there's a more mundane (if that's the right word!) explanation: one that involves the biggest known void in the universe.

Read more (New Scientist)

What if light is not as fast as we thought?

Supernova 1987A

Supernova 1987A
If physicist James Franson of the University of Maryland is right, the speed of light may be slower than the value normally accepted – 299,792,458 meters per second. His suggestion comes from observations of supernova SN 1987A. Both neutrinos and photons were detected on Earth coming from the blast. But scientists were puzzled to find that the photons arrived 4.7 hours later than expected. At the time, this was put down to the possibility that the photons came from another source. But Franson has offered another theory: namely, that photons from the explosion split many times into electrons and positrons during their passage to Earth before, each time, recombining back into photons. Such splitting, he reasoned, would lead to a gravitational differential between the electrons and positrons, and a minute energy impact when they recombined — enough to result in a tiny slowdown during travel.

Read more (Physorg)

Hunt is on for targets after New Horizons flies past Pluto

Artwork of New Horizons at Pluto

Artwork of New Horizons probe in the Kuiper Belt
Mission controlers of the New Horizons spacecraft, which will fly past the dwarf planet Pluto and its collection of moons, including out-sized Charon, next July, have a problem: they don't know where to send New Horizons next. Whatever happens after the Pluto encounter, the probe is bound on an exit trajectory from the solar system. It will join the twin Voyagers, 1 and 2, and Pioneers 10 and 11, on a journey to the stars. But before that, it has to cross the Kuiper Belt, a region rich in objects, large and small, that are relics of the early days of planet formation. The trouble is, there are no obvious, known targets, beyond Pluto, reachable by New Horizons, of which astronomers are presently aware. This is where Hubble comes in. The Time Allocation Committee for the orbiting telescope has recommended that it be used to seek out possible objects among trajectories that are attainable by New Horizons, given its limitations of fuel supply and rocket thrust. But the search will not be easy: the objects in question may be no more than a few tens of miles across and are darker than coal.

Read more (NASA)

Oldest known habitable planets found – just 13 light-years away

Diagram showing the habitable zones around Kapteyn's Star and the Sun and the planets within them

Size comparison of Kapteyn b and Earth
Two planets have been found around Kapteyn's Star, an old red dwarf that lies a mere 13 light-years from the Sun. One of the planets, Kapteyn b, is a super-Earth, at least 5 times as massive as our own world, moving in an orbit that is less than half the size of Mercury's orbit around the Sun. Even at this small distance from its star, Kapteyn b receives only 45% of the light that we enjoy from the Sun, so that if it were Earth-sized any water on its surface would be frozen solid. But because Kapteyn b is a super-Earth it very likely has a denser atmosphere which may raise its surface temperature enough to support liquid water. What's more it is about 11.5 billion years old – more than double the age of the Earth – so that it has had plenty of time to evolve life.

Read more (University of Puerto Rico at Arecibo)

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