No alien megastructure around mysterious ‘Tabby’s star’, analysis shows

Stand down space cadets: there is (sadly) no alien megastructure around star KIC 8462852, also known as Tabbys star

As if a divisive Star Wars film wasnt bad news enough this Christmas, now an analysis by more than 200 astronomers has been published that shows the mysterious dimming of star KIC 8462852 is not being produced by an alien megastructure.

The evidence points most strongly to a giant cloud of dust occasionally obscuring the star. The cloud was most possibly produced by the collision of two comets or the break-up of a single one. Another option is that the star itself is undergoing some sort of internal convulsion that astronomers have never seen before.

KIC 8462852 is approximately 1,500 light years away from the Earth and hit the headlines in October 2015 when data from Nasas Kepler space telescope showed that it was dimming by unexplainably large amounts. The stars light dropped by 20% first and then 15% making it unique. Even a large planet passing in front of the star would have blocked only about 1% of the light.

For an object to block 15-20%, it would have to be approaching half the diameter of the star itself. With this realisation, a few astronomers began whispering that such a signal would be the kind expected from a gigantic extraterrestrial construction orbiting in front of the star and the idea of the alien megastructure was born.

Tabetha Boyajian, then at Yale University and now at Louisiana State University, led the investigations into the mysterious signals. It was after her that the star was nicknamed Tabbys star. She said at the time that a constant monitoring programme was needed to watch the star for more dips.

Todays new analysis is the result of that programme. It was funded by a Kickstarter campaign that attracted support from more than 1,700 people and raised more than $100,000. In partnership with the Las Cumbres Observatory, a privately-funded organisation that operates 21 telescopes at eight sites around the world, the astronomers monitored the star from March 2016 to December 2017.

In that time they recorded four more dips, though none were as dramatic as the originals, reaching only a percent or two. These were named by the Kickstarter supporters as Elsie and Celeste, Skara Brae and Angkor. Significantly for the analysis, the dimming events were captured at multiple wavelengths.

If an alien megastructure had been causing the drop in light, being a solid object, it would block all wavelengths in the same way, at the same time. Thats not what the team saw. Instead, different wavelengths of light dropped by different amounts. This is exactly what you would expect from starlight passing through a tenuous dust cloud.

It happens because dust grains scatter light depending on its wavelength. Blue light, which has short wavelengths, is scattered more easily than red, which has longer wavelengths. This is why our sky is blue; that colour has been scattered out of the suns direct light by the molecules in the air.

In the case of Tabbys star, the new observations show that it dims more at blue wavelengths than red. Thus, its light is passing through a dust cloud, not being blocked by an alien megastructure in orbit around the star (#sadface).

The new analysis of KIC 8462852 showing these results is to be published in The Astrophysical Journal Letters. It reinforces the conclusions reached by Huan Meng, University of Arizona, Tucson, and collaborators in October 2017. They monitored the star at multiple wavelengths using Nasas Spitzer and Swift missions, and the Belgian AstroLAB IRIS observatory. These results were published in The Astrophysical Journal.

While it is not aliens this time, the story serves as a valuable reminder that unexpected signals of this kind are definitely the ones to look out for. Something unexplainable in some unexpected observation rather than a deliberate radio message to us is probably the way we are going to spot the presence of extraterrestrials if theyre out there in the first place, of course.

Stuart Clark is the author of The Search for Earths Twin (Quercus).

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At 140 a mile, how does Elon Musks moon trip compare with other journeys?

From car to rail, its hard to find a terrestrial journey that matches SpaceXs astronomical cost

It is a stratospheric sum but it does, at least, include the return journey. Elon Musk, the billionaire American transport visionary, has suggested that the first, so far unnamed, passengers on his SpaceX flight round the moon will pay about $70m (56m).

Musk says the journey, tentatively scheduled for 2018 on an untested Falcon Heavy rocket, will cover up to 400,000 miles, although the Apollo 13 crew, on their trip to the moon in 1970, were a record 248,655 miles from Earth, so this figure seems modest if anything. Either way, 400,000 miles (about 16 times the circumference of Earth) for 56m is equal to about 140 a mile, which is easier to fathom. But how does it compare with terrestrial journeys?

Rail: The priciest rail ticket in the UK, the home of extortionate rail travel, is reportedly 501 for the 480-mile anytime return from Shanklin on the Isle of Wight to Buxton in Derbyshire (includes the ferry). Thats a little more than 1 a mile. The most expensive season ticket by distance, from Harlow Town in Essex to London Liverpool Street, is less than 40p a mile for a full-time worker.

Car: A Ferrari F12tdf has the joint worst fuel economy, according to US government figures, with as little as 12 miles a gallon. At current pump prices, that equates to about 45p a mile. Even adding depreciation, insurance and the 340,000 cost of the car its a lot cheaper than space.

Bus: Buses are cheap, right? Not if you take the No 47 from Lewisham Park in south-east London to Lewisham Hospital, 135 metres up the road. At 1.50 that equates to almost 18 a mile.

Air: You would think air travel comes close, but the worst damage you can do on an airliner is a 55,000 return ticket from London to Melbourne (20,000 miles total) in Etihads penthouse suite. But thats only 2.75 a mile.

Tube: The closest you can get to matching the cost of lunar travel is on the London Underground. The shortest Tube journey is the 350 metres, from Covent Garden to Leicester Square. A cash ticket costs 4.90, which equates to almost 23 a mile, about a sixth of the cost of a trip to the moon and back and a lot quicker.

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7 Earth-Like Worlds Orbit a Star So Cool, You Didnt Know It Existed

Forty light years away, a small, orange star called Trappist-1 sits unnoticed in the sky. You can’t see it with your bare eyes—it burns colder than the brightly shining stars that fill the night sky, the ones that have inspired millions of people to imagine life beyond Earth. But most stars in the galaxy are neither big nor bright. And it’s those abundant, dim dwarfs that might actually be the best place to look for worlds capable of supporting life.

Now, scientists have discovered seven Earth-like exoplanets orbiting Trappist-1. Each world is nearly the same size and mass as our own world. And more exciting, three of these worlds orbit within a zone—not too close, not too far—in which water can exist without freezing or boiling. All these factors have the European scientists who closely study this exoplanet system excited that this might be the best place yet to squint into the inky black of night for signs of life.

Trappist-1 is an ultracool dwarf star. It is barely bigger than Jupiter, and burns about 6,500 times cooler than the sun. That’s so cool—ultracool, man—that its core is barely warm enough to fuse hydrogen atoms into helium. In 2016, a team led by Michal Gillon from the Universit de Lige in Belgium wrote the first report of exoplanets orbiting the star. Today, in Nature, they more than double their previous analysis, as well as offer further details about what these planets might look like. “They form a very complex system, with the planets all being close to each other, and close to the star, which is reminiscent of the system of moons around Jupiter,” says Gillon.

ESO/M. Kornmesser

This little star system has already offered plenty of secrets. Partly, that’s due to how tightly the planets spin around the dim bulb in the center. Exoplanet hunters determine many attributes of their quarry using a process called transit measuring, which captures the silhouette of a planet as it passes between Earth and its star. Because the orbits of all the rocky worlds in the Trappist-1 system are so tight, Gillon and his team were able to make 34 transit observations in just a few months—and identify the seven separate planets.

Among that data are indications that some of these worlds could support life. “What potentially habitable means is liquid water,” says Gillon. Only three worlds exist in the theoretical “Goldilocks Zone” where their surfaces would receive life-incubating levels of stellar energy. But all seven could, theoretically, have liquid water. The planets pass so closely that they pull on each other as they pass by, creating warming tidal forces—the same kind of heating that could give Jupiter’s frozen moon Europa an underground ocean.

The transit analysis also let Gillon’s team estimate the planets’ sizes. As you can see in the graphic below, they’re each within 10 percent of the size of Earth:

That graphic, though, in no way represents what these exoplanets actually look like. (Okay, maybe a little bit. The planets closer to Trappist-1 are probably warmer than those further out.) Most of what scientists learn about the look of faraway worlds comes from analyzing their atmospheres. Pluto is barely two light hours from Earth, and nobody on Earth knew what it looked like until researchers shot a space probe to go visit. New Horizons took nearly 10 years to reach Pluto from Earth; a similar mission would take many centuries to reach Trappist-1, which is 40 light years away. Even one of the laser-propelled microsats being developed by Breakthrough Starshot would need about 180 years for the trip.

But astronomers can get a pretty good idea whether these exoplanets carry life just by observing the light of Trappist-1 as it shines through their atmospheres. “Plenty of science fiction books say ‘If you have oxygen, you have life,’ but that is not true,” says Gillon. Instead, they’ll look for telltale chemical traces of molecules like carbon dioxide and ozone. That work begins soon, and will use a new set of telescope systems called SPECULOOS—four, 1 meter infrared instruments placed around the world. That way, astronomers can constantly look into the black of night for signs of life, no matter how dim they might be.

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88 New Satellites Will Watch Earth, All the Time, All the Places

The satellite company Planet is used to breaking records. In 2014, a rocket exploded with a payload of the company’s satellites inside—26, the biggest loss ever. And today, Planet will launch the largest sat fleet ever, on a rocket carrying the most satellites in history, when it sends 88 new craft from the Satish Dhawan Space Center in Sriharikota, India.

These devices, called Doves, will flock with already-orbiting instruments to capture pictures of the Earth. They’re tiny, weighing less than 11 pounds. But with their powers combined, they can track much more of the Earth than massive satellites from military-industrial juggernauts like DigitalGlobe. Even more, Planet just this month purchased another mini-sat company, Terra Bella, from Google, to amp up its space surveillance. And that means it can sell more data—data perhaps about where you live or work or play—for more money.

What kind of data, you ask? Images of farmland, for one, which can help customers measure crop yield. And if a tsunami inundates a coastline, satellite data can direct relief efforts to the right places. Retailers can take stock of parking lots to understand shopping schedules. A mining company can learn how much material is coming out of their remote site—or their competitors’. And governments can spy on whatever governments spy on.

Planets blog post announcing their latest launch says itwill be imaging the entire Earth daily. That’s not quite right: Itcan only image around 58 million square miles of the globe’s 193 million. Earth’s landmasses are right around the 58 million mark—so the truer claim is that Planet will be imaging the entirety of Earths earth daily.

But still—that’s a lot. On the strength of its 55 currently-operating satellites, the company has already raised $183 million of capital. And with the 88 sats launching today and Terra Bella’s seven more, Planet is poised to become the most powerful provider of daily Earth imagery.


All Your Base Are Belong to Planet

Google first bought Terra Bella for $500 million in 2014, back when they were called Skybox Imaging and had just two satellites. But after a few-year foray, Google decided it doesnt want to play this particular space game. That makes sense to Walter Scott, who founded DigitalGlobe. Space is hard, he (and everyone else) says. Our customers generally find it more cost-effective to be buyers rather than owners.

And that is, in fact, what Google plans to do. When Google handed Terra Bella off for an undisclosed figure, they also signed a multi-year agreement to buy data back from Planet. Now, Google gets the images it wants without the pain of procuring rocket space, having satellites blow up, or competing with Planet—which, presumably, doesnt want to be bought because it is doing just fine on its own, thank you very much.

Meanwhile, Terra Bellas satellites will make up for the Doves’ deficits. The acquisition wasnt just an accident, where we got drunk one day,” says Planet founder Will Marshall. Each of the seven sats has four to six times the resolution of Planet’s model, but they can’t provide the same constant coverage. So the Doves can watch for changes in their high-throughput, lower-resolution images, and if they see a shift—flooding where land was dry, a bunch of tanks next to a formerly quiet oil pipeline—Planet can task one of the bigger satellites to take a better picture.

Another acquisition recently filled in another of the company’s gaps. Planet’s images work great for the recent past, and the future. But their flock didnt hatch long ago. So when they purchased the more aged Earth-observation company BlackBridge in 2015, they gained access to its RapidEye satellites and their archives, extending their imagery back to 2008. On top of that, Planet customers can now look at Landsat 8 and Sentinel-2 archives, which show Earth in different wavelength bands, in the same portal where they view Dove and RapidEye data.

Win, win, win, win.

Now, the other Earth-facing players still have a place in Planet’s world. DigitalGlobe can only image 1.5 million square miles per day to Planet’s 58 million, but it can send customers pictures at 11.8-inch scale—essentially resolving a laptop into its own single pixel, from space. And it is expanding its breadth, partnering with Saudi Arabian governmental organizations to launch a medium-resolution set of satellites.

But when it comes to whole-Earth imagery—or whole-landmass, anyway—Planet has the lead. And its customers, for the right price, can extract nearly endless information from the satellites’ images. Thats what power looks like.

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Mars lander smashed into ground at 540km/h after misjudging its altitude

Schiaparelli thought it had landed on Mars when in fact it was still 3.7km above the surface, says European Space Agency

A tiny lander that crashed on Mars last month flew into the red planet at 540km/h (335mph) instead of gently gliding to a stop, after a computer misjudged its altitude, the European Space Agency has said.

Schiaparelli was on a test-run for a future rover meant to seek out evidence of life, past or present, but it fell silent seconds before its scheduled touchdown on 19 October.

After trawling through vast amounts of data, the ESA said on Wednesday that while much of the mission went according to plan, a computer that measured the rotation of the lander hit a maximum reading, knocking other calculations off track.

That led the navigation system to think the lander was much lower than it was, causing its parachute and braking thrusters to be deployed prematurely.

The erroneous information generated an estimated altitude that was negative that is, below ground level, the ESA said in a statement.

This in turn successively triggered a premature release of the parachute and the backshell [heat shield], a brief firing of the braking thrusters and finally activation of the on-ground systems as if Schiaparelli had already landed. In reality, the vehicle was still at an altitude of around 3.7km (2.3 miles).

The 230m ($251m) Schiaparelli had spent seven months travelling 496m kilometres (308m miles) onboard the so-called Trace Gas Orbiter to within a million kilometres of Mars when it set off on its own mission to reach the surface.

After a scorching, supersonic dash through Marss thin atmosphere, it was supposed to glide gently towards the planets surface.

For a safe landing, Schiaparelli had to slow from 21,000km/h (13,000mph) to zero, and survive temperatures of more than 1,500C (2,730F) generated by atmospheric drag.

It was equipped with a discardable, heat-protective shell, a parachute and nine thrusters to decelerate, and a crushable structure in its belly to cushion the final impact.

The crash was Europes second failed attempt to reach the surface of Mars.

Giant crater seen in ESA images of Schiaparellis crash landing on Mars

The first attempt, in 2003, also ended in disappointment when the British-built Beagle 2 robot lab disappeared without trace after separating from its mothership, Mars Express.

Since the 1960s, more than half of US, Russian and European attempts to operate craft on the Martian surface have failed.

Schiaparelli and the Trace Gas Orbiter comprised phase one of a project dubbed ExoMars through which Europe and Russia are seeking to join the US in operating a successful rover on the planet.

The next part of the mission is the start of the Trace Gas Orbiters mission in 2018, sniffing Marss atmosphere for gases potentially excreted by living organisms.

The rover will follow, due for launch in 2020, equipped with a drill to search for remains of past life, or evidence of current activity, up to two metres below the surface.

While life is unlikely to exist on the barren, radiation-blasted surface, scientists say traces of methane in the atmosphere may indicate something is stirring underground possibly single-celled microbes.

European space officials have insisted that any problems encountered by Schiaparelli would inform the design of the future rover.

In some ways, were lucky that this weakness in the navigation system was discovered on the test landing, before the second mission, ESAs Schiaparelli manager, Thierry Blancquaert, said.

This is still a very preliminary conclusion, David Parker, ESAs director of human spaceflight and robotic exploration, said of Wednesdays findings. The full picture will be provided in early 2017 by the future report of an external independent inquiry board.

But we will have learned much from Schiaparelli that will directly contribute to the second ExoMars mission being developed with our international partners for launch in 2020.

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Hello, is this planet Earth? by Tim Peake – in pictures

Based on over 150 photographs taken by British astronaut Tim Peake, the book documents his six months on the International Space Station

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