UFO'S of UAP'S, ASTRONOMIE, RUIMTEVAART, ARCHEOLOGIE, OUDHEIDKUNDE, SF-SNUFJES EN ANDERE ESOTERISCHE WETENSCHAPPEN

The science fiction movie "Arrival," which opened in theaters this month, poses tantalizing questions about how humans might make contact — and eventually communicate — with intelligent aliens. The much-hyped film has renewed people's interest in the search for intelligent life elsewhere in the universe. But what would happen if humans really did make contact with an intelligent alien civilization? If E.T. calls, is there a plan?

The answer is yes, and no, said astronomer Seth Shostak, who leads efforts to detect radio signals from extraterrestrial civilizations at the SETI Institute in Mountain View, California.

"There are some protocols, but I think that's an unfortunate name, and it makes them sound more important than they are," Shostak told Live Science.

In the 1990s, Shostak chaired a committee of the International Academy of Astronautics (IAA) that prepared a revised version of the "post-detection protocols" for researchers who watch for possible alien transmissions using radio telescopes, a field known as SETI (short for the Search for Extraterrestrial Intelligence).

The protocols were first drawn up in the 1980s to help scientists in the United States and the Soviet Union share information about any potential SETI signals. But, Shostak explained, the SETI post-detection protocols are guidelines for governments and scientists, rather than a global action plan for dealing with alien contact.

A still from the movie "Arrival" Paramount

"They say, 'If you pick up a signal, check it out ... tell everybody ... and don't broadcast any replies without international consultation,' whatever that means," he said. "But that's all that the protocols say, and they have no force of law. The United Nations took a copy of the early protocols and put them in a file drawer somewhere, and that's as official as they ever got.""

Men in Black

"In the movie "Arrival," spaceships land in several cities around the world, and a linguist (portrayed by actress Amy Adams) and a physicist (played by actor Jeremy Renner) are recruited as part of an international effort to try to communicate with the aliens and find out why they are here.

In real life, apart from the protocol dictating that researchers should share news about SETI signals with other astronomers around the world, Shostak said he is not aware of any government-level plans or established procedures in case of an alien contact, whatever form it might take.

And it seems there really are no "Men in Black," shadowy government investigators of UFO-lore, depicted in the comedy sci-fi movie series starring Will Smith and Tommy Lee Jones.

"If [the government] could afford the 'Men in Black,' then they could afford to support SETI," Shostak joked.

But the U.S. government has shown no interest in SETI research so far, he said. "It's not a government program, so they have nothing to do with it. I would love to see some interest from them, but I never have," he added.

Radio Telescope, Arecibo Observatory, Puerto Rico

Worlds largest single-dish radio telescope, the Arecibo Observatory, Arecibo, Puerto Rico.

UniversalImagesGroup / UIG via Getty Images

After one early SETI "false alarm,"which eventually turned out to be a signal from a European research satellite, the only response was from journalists.

"In 1997, we got a signal that looked pretty promising for most of the day. We thought it was possibly the real deal," Shostak said. "I kept waiting for the 'Men in Black' to show up — they didn't. I kept waiting for the Pentagon to call. I kept waiting for the White House to call. They didn't call. But The New York Times called."

Close encounters

In a review of the science and speculations about extraterrestrials, published as "Xenology: An Introduction to the Scientific Study of Extraterrestrial Life, Intelligence and Civilization" in 1979, the author and scientist Robert Freitas described a purported military briefing in Washington, D.C., in 1950 that outlined potential U.S. military responses to alien contact.

The supposed military plan, which became known as "Seven Phases to Contact," was first reported in a 1967 book on UFOs by the American broadcaster and UFOresearcher Frank Edwards.

But Shostak said he has seen no sign of any extraterrestrial action plan for U.S. government agencies or the military. "As far as I know, there's nothing, and I think I would have heard something because of the [SETI] false alarms," he said.

While detecting an alien radio signal would be different from encountering spaceships that landed on Earth, Shostak doesn't think protocols will play a big part in how we respond.

"Some people asked me at a conference last week, 'What plan does the military have to deal with aliens should they land?' And I said, 'I don't know … but to the best of my knowledge, they don't have a plan.

'"Shostak noted that any aliens who could travel here in a spacecraft would need to be centuries or thousands of years more technologically advanced than humans are now, so it's almost impossible to imagine the consequences of contact between the species, let alone the thought of developing a plan to deal with them.

"It would be like the Neanderthals having a plan in case the U.S. Air Force showed up," he said.

Calling planet Earth

Although the aliens in "Arrival"helpfully travel to Earth in faster-than-light spaceships, willing and ready to talk, Shostak said a more likely "first contact" scenario would be the detection of a SETI radio signal, perhaps from a source hundreds or thousands of light-years away.

That means it could take centuries for the aliens to receive any reply transmitted from Earth in an effort to communicate with them, he said. As such, there might not be any real hurry to decide what to say.

File - A car moves along the Extraterrestrial Highway near Rachel, Nevada, in this Wednesday, April 10, 2002 file photo. The ET highway was established by the Nevada Legislature in 1996 and runs along the eastern border of Area 51, a military base on the Nevada Test Site. George Washington University's National Security Archive obtained a CIA history of the U-2 spy plane program through a public records request and released it Thursday Aug. 15, 2013. LAURA RAUCH / ASSOCIATED PRESS

And if E.T. does call, what should humans say in response? Some scientists, including British physicist Stephen Hawking, have expressed concern about "Active SETI" programs designed to transmit messages from Earth to any aliens that might be listening. Hawking warned of the potential threat posed by unknown extraterrestrials and their alien motivations.

There's also the difficult matter of making the right first impression in any extraterrestrial chat, Shostak said.

"I've been to several conferences where people discuss whether we should tell [aliens] all the bad things about humanity, or just the good things, and that sort of thing," he said. "But I think that is terribly overdrawn. To me, that would be like the indigenous people of Australia seeing Capt. Cook coming over the horizon in his ship, then saying, 'We're going to have a couple of conferences to discuss what we're going to talk to these guys about, and what language we'll use' — [but] it doesn't matter."

Shostak pointed out that humans have already been broadcasting newsinto space for decades, in the form of television and radio signals, and so it's probably too late to keep quiet.

"Those signals have been going out into space since the Second World War, so we've already told them we're here," he said.

Original article on Live Science.

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Not Super, But Still Brilliant: What Causes Regular Novas? — The first lithium ever found in a star explosion was pinpointed in this bright nova (center). Nova Centauri 2013, the exploding star, was captured in July 2015 by the New Technology Telescope at ESO's La Silla Observatory.
**Credit: ESO**

Paul Sutter is an astrophysicist at The Ohio State University and the chief scientist at COSI Science Center. Sutter is also host of Ask a Spaceman, RealSpace and COSI Science Now.

Imagine how surprised Danish astronomer Tycho Brahe would have been when he examined a "new star" that appeared in the sky in November 1572. Actually, you don't have to imagine it, because I'm about to describe it.

Of course, "new stars" had appeared and been noticed all throughout history, and their origins were always a source of wonder, confusion and argument. Comets were generally thought to be some sort of atmospheric phenomenon (perhaps the premodern equivalent of UFOs explained by "swamp gas and weather balloons"). And an occasional new star? Uh, how about a comet … without a tail? Sure, that works.

Either way, it was important to early European thinkers that messy stuff in the sky stayed in the sky, and not in the stars. In their worldview, the imperfect, dirty, messy, sloppy, Earthly realm stood in stark contrast to the mechanical clockwork perfection of the heavens. If something weird happened in the sky, they thought, it should be a part of Earth and not the celestial. [Know Your Novas: Star Explosions Explained (Infographic)]

So now we get to Brahe's surprise. Just before the dawn of the telescope age, his observatories provided the most precise measurements of the heavens possible with the unaided eye. One technique available to him for measuring heavenly distances was parallax — when nearby objects appear to move back and forth as a watcher switches viewpoints, while more distant objects hardly seem to move at all. Measure the back-and-forth, do a little trigonometry and voilà — you have a distance.

If the "new star" of 1572 was truly an atmospheric object, Brahe's observatory should have been able to measure its parallax. But it couldn't — the object was too distant — and Brahe was surprised. The new star was seated firmly in the heavens, embedded in the supposedly perfect and unchanging celestial realm.

A star is born

Brahe described his observations in a manuscript with a sufficiently braggadocio title: "Concerning the star, new and never before seen in the life or memory of anyone." This work set off a revolution as astronomers grew to realize that stuff in space is not at all perfect and is actually kind of messy.

We now know that Brahe's "stella nova" ("new star") was actually a supernova, but for centuries, the Latin word "nova" was attached to anything new in the sky. It wasn't until the 1930s that stricter definitions were sorted out: If a star completely blew up, it was a supernova; if it didn't, it was a regular nova.

But even that wasn't enough, as modern observers discovered different classes of objects, mechanisms and processes that led to outbursts in the sky. "Supernova" got to stay "supernova," with newly labeled subtypes to indicate the specific astrophysical process, but "nova" was switched to "cataclysmic variable star," because… well, I don’t really know, but that's the world we live in.

When stars get fat

That longer name does serve at least one useful purpose, though: It indicates that something violent is happening to some stars to make them dramatically change their brightness. There are a few mechanisms that can cause the change, including the always-popular stars ramming into each other. But the most common scenario — and the situation that astronomers typically depict when the old term "nova" gets casually tossed around in hallway conversations — happens when two stars live together.

When stars are born together, one is more massive than the other. It could be by a little; it could be by a lot. But either way, the more massive of the duo will churn through its supply of hydrogen faster, as its increased gravitational pressure drives the fusion rate in its core to a frenetic pace. Meanwhile, the lower-mass sibling carefully sips at its fuel reserves, burning slowly and steadily.

With enough time, the larger star will run out of hydrogen, evolve into a red giant and briefly ignite helium. After violently spewing its layers of atmosphere into the surrounding system, it will finally settle down into a comfortable white-dwarf retirement.

The white dwarf — an unassuming ball of unfused and inert carbon and oxygen — can remain stable for trillions of years. That is, until its companion begins to undergo its own violent paroxysms.

Eventually, the smaller companion will run out of fusible hydrogen and enter its own end-of-life red-giant stage. If it were all alone in space, it would simply get larger. (Our own sun will likely engulf the Earth at this stage, but that's a different article.) But tied to its white-dwarf sibling in the binary system, the loosely connected outermost layers of the red giant's atmosphere can work their way onto the surface of the companion.

This slipping of gas from one star to another occurs via a so-called Roche lobe, a funnel-like extension of the red giant where the white dwarf's gravity starts to exert its influence. [Watch this video for more about Roche lobes.]

100,000 suns

At first, this process is rather benign: The red giant's atmosphere of hydrogen simply accumulates on the white dwarf. Because the dwarf itself is made of heavy carbon and oxygen, the new supply of hydrogen doesn't really go anywhere, instead building up a thick blanket of material.

If the process stopped there, nothing interesting would really happen. But the process doesn't stop there.

At some point, the pressures on the bottom layer of hydrogen reach a critical point, and boom — the whole thing goes up in a single nuclear flash. If the detonation is sufficiently powerful to ignite carbon fusion, the whole white dwarf is consumed in a supernova, but if only the hydrogen layer goes off, it's a good old-fashioned regular nova.

Most of the time, such an explosion just happens once, with the white dwarf temporarily increasing in brightness by 50,000 to 100,000 times. But there are a few known cases of repeated events that we don't fully understand.

No matter what, the universe is a messy place.

Learn more by listening to the episode "How do (regular) novas work?" on the Ask A Spaceman podcast, available on iTunes and on the Web at http://www.askaspaceman.com. Thanks to @DesRon94 and Tim R. for the questions that led to this piece! Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter.

Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.