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"Oumuamua, the first object ever seen passing through our solar system from interstellar space, was thought to be emitting gas like a comet to explain its weird motion," reports Syfy Wire, "but a new idea is that the comet is just very, very porous."

Astronomer Phil Plait writes: It was hard to tell what it was; it was too small, faint, and far away to get good observations, and worse, it was only seen on its way out, so it was farther from us literally every day. Then another very weird thing happened: More observations allowed a better determination of its trajectory, and it was found that it wasn't slowing down fast enough. As it moves away, the Sun's gravity pulls on it, slowing it down...but it wasn't slowing down enough. Some force was acting on it, accelerating it very slightly... A new paper has come out that might have a solution, and it's really clever. Maybe 'Oumuamua's not flat. Maybe it's fluffy... [And thus moved by the force of sunlight giving it a tiny push]

When stars are very young, they have a huge disk of material swirling around them; it's from this material that planets form. Out far from the star, where temperatures in the disk are cold, teeny tiny grains of dust and water ice can stick together in funny shapes, creating fractals... Materials made in a fractal pattern can be very porous, and in fact out in that protoplanetary disk around a young star, physical models show that objects can grow fractally until they're as big as 'Oumuamua, and have those extremely low densities needed to account for its weird behavior. So 'Oumuamua doesn't have to be a spaceship. It just has to be a snowflake! A three-dimensionally constructed phenomenally porous low-density snowflake... [T]he new paper suggests it came from a nearby star, and one that's relatively young (less than 100 million years). It formed out in the disk, and got ejected somehow, likely from a planet forming nearby giving it a boost from its gravity.
"I certainly hope we find more beasties like this one," Plait writes. "They can tell us so much about how planets form in other star systems, which is pretty hard to figure out from dozens or hundreds of light years away.

"It's a lot easier when they obligingly send bits of their building materials to us."

The Bad Astronomer writes: A nearby star, HD 186302, was almost certainly born from the same cloud of gas the Sun was 4.6 billion years ago. Astronomers have found it has an almost identical chemical composition as the Sun, is on a similar orbit around the Milky Way, and has the same age (within uncertainties). Interestingly, it's only 184 light years away, implying statistically many more such stars are waiting to be discovered.

New submitter FranklinWebber writes: Spacecraft Hayabusa2 is approaching its target, asteroid Ryugu, after a three-and-a-half year trip. The Japan Aerospace Exporation Agency (JAXA) has released photos of the asteroid taken from a distance of several hundred kilometers and showing a diamond-shaped object.

Like its predecessor spacecraft a decade ago, Hayabusa2 is designed to collect samples from an asteroid and return them to earth. JAXA explains: "A C-type asteroid, which is a target of Hayabusa2, is a more primordial body than Itokawa [the target of Hayabusa and an S-type], and is considered to contain more organic or hydrated minerals.... we expect to clarify the origin of life by analyzing [samples from Ryugu]."

The Bad Astronomy blog has more discussion of the mission: "The spacecraft will deploy an impactor that will slam a 2.5 kilo piece of copper into the surface at 2 km/sec. This will dig down into the asteroid, revealing material underneath, which can then be analyzed to understand Ryugu's interior."

An anonymous reader quotes Syfy.com: There's a new documentary warning about the perils of artificial intelligence out there, and Elon Musk wants you to see it. So much so that he's making it available to stream for free this weekend. The documentary -- Do You Trust This Computer? -- explores the rise of machine intelligence and its possible consequences... Check out the trailer, and then proceed to be creeped way the hell out.... "It's a subject that I feel we should be paying close attention to," said Musk in a news release. "I think it's important that a lot people see this movie, so I'm paying for it to be seen to the world for free this weekend."
Musk attended the premier of the film with the creator of HBO's Westworld, and tweeted Saturday that the video had 5 million views in just 36 hours.

Musk himself is interviewed in the film, warning of the dire possibility of "an immortal dictator from which we can never escape."

Zaiff Urgulbunger writes "According to the BBC, 'Cult classic sci-fi series Blake's 7 is to be remade for the Syfy network, it has been announced. FremantleMedia International said 13 hour-long episodes will be written by Heroes writer Joe Pokaski.' Here's hoping the special effects budget will be higher than for the original series! Also, I'm hoping that the Liberator is of similar design and includes Zen — the ships computer."