Space News/UFO's Etc...(Discussion/Pics/Vids)

[Ryu]

I've liked astronomy since I was a little kid. Fascinating topic!

and I love new discoveries underwater or in orbit

[ilan]

Is ‘Oumuamua an Interstellar Pancake?
Kelly Beatty | March 27, 2018

A new analysis of more than 800 telescopic observations suggests that our first known interstellar visitor could have the shape of a flattened disk.


Artist's impression of ʻOumuamua

It's been about five months since Robert Weryk, observing with the PanSTARRS 1 telescope atop Haleakala on Maui, discovered the first object (other than dust particles) known to have entered our solar system from interstellar space. But 1I/‘Oumuamua, as it came to be named, zipped away from Earth too quickly to give astronomers more than a few weeks to observe it. (‘Oumuamua is a combination of two Hawai'ian words that roughly mean "the first scout," and 1I indicates the first cataloged interstellar object.)

When I reported the early findings about this surprising interloper back in December, astronomers were fixated on its slightly reddish color and its tenfold swings in brightness (up to 2½ magnitudes). Assuming that it's highly elongated, 5 to 10 times longer than its width, most researchers imagined this object pinwheeling end over end with a spin axis through its shortest dimension.

But Where Did ‘Oumuamua Come From?

Aside from puzzling out the object's shape and spin, many theorists are tackling the question of where ‘Oumuamua came from and how it got here. It came from the direction of the constellation Lyra, passing through at about 26 km (16 miles) per second. This incoming trajectory doesn't implicate any specific star as the source, but it's likely drifted through interstellar space for tens or hundreds of millions of years.

Early in our solar system's history, gravitational slingshots from the giant planets and the Sun cast countless objects (perhaps trillions of them) out into deep space, never to return. So ejection from another star system seems the most likely way that ‘Oumuamua escaped, but even then it's complicated.

We'll likely never know the real story, but astronomers have redoubled their efforts to spot other interstellar interlopers. Calculations by Aaron Do (University of Hawai'i) and two colleagues suggest interstellar escapees should average about one for every 5 cubic astronomical units of space. In other words, they conclude, "there are likely several of these objects in the inner solar system at any given time."

[ilan]

A sun is a star at the center of an interplanetary system. Most likely, a high percentage of stars have planets orbiting them, so they are suns, too. The star at the center of our solar system is named the Sun, with a capital S. All others are called suns, with a small s.

[ilan]

Dark matter and dark energy are associated with all kinds of astronomical phenomena. If they were eliminated as an explanation for the expanding universe, they would still play a big part in a host of other theoretical explanations and indirect observations. Plus, there ain't nothing cooler than the notion of a black hole being a gateway to an alternate universe!

[4me2c]

Too Much to Re-post :

https://www.csmonitor.com/Science/2014/0127/Stephen-Hawking-makes-shocking-revelation-on-black-holes

Stephen Hawking makes shocking revelation on black holes

Stephen Hawking, author of 'A Brief History of Time' makes a U-turn on black holes. What goes into black holes can now escape, although in a much mangled form, he suggests. ...

Stephen Hawking's latest paper on black holes is raising some eyebrows.

In a four-page article titled "Information Preservation and Weather Forecasting for Black Holes," published through arXiv, an archive for electronic preprints of scientific papers, Dr. Hawking contradicts his earlier proposed theory over the existence of "event horizons," the proverbial point of no return surrounding a black hole.

The event horizon is a proposed boundary around a black hole. On the other side of it, the gravitational pull of the black hole is so strong that, in order to escape it, an object would have to be moving faster than the speed of light, a feat that almost all physicists agree is impossible. ...

But instead of there being event horizons, "there are however apparent horizons which persist for a period of time. This suggests that black holes should be redefined as metastable bound states of the gravitational field," writes Hawking.

These "apparent horizons" for a certain time can retain "information" that could be in the form of matter, before eventually releasing them. In other words, if Hawking is correct, black holes might not be so black after all.

But what would happen if an astronaut fell into a black hole?

Astrophysicists often use the term "spaghettification" to describe our fictional astronaut's plight. The gravitational pull of the black hole increases so rapidly that the differences between the astronaut's head and toe are so great that he gets stretched into a noodle. ...! More with the Link...

[ilan]

What Is a Black Hole?
This is part of the NASA Knows series


Artists view of our galaxy, the Milky Way. At its center is a supermassive black hole.

A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.

Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.

How Big Are Black Holes?
Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object.

Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way.

The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.

How Do Black Holes Form?
Scientists think the smallest black holes formed when the universe began.

Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.

Scientists think supermassive black holes were made at the same time as the galaxy they are in.

If Black Holes Are "Black," How Do Scientists Know They Are There?
A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. Scientists can study stars to find out if they are flying around, or orbiting, a black hole.

When a black hole and a star are close together, high-energy light is made. This kind of light can not be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.

Could a Black Hole Destroy Earth?
Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.

Even if a black hole the same mass as the sun were to take the place of the sun, Earth still would not fall in. The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now.

The sun will never turn into a black hole. The sun is not a big enough star to make a black hole.

How Is NASA Studying Black Holes?
NASA is using satellites and telescopes that are traveling in space to learn more about black holes. These spacecraft help scientists answer questions about the universe.
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Stephen Hawking explains Black Holes in 90 seconds



Although Hawking mentions particles can escape a Black Hole, so they're not as black as we once thought, they are still very dense and very black, and they gobble up stars and other matter. - ilan

[ilan]

That is so science, though! Theories are works in progress. They aren't statements of fact. Theories are constantly being tweaked to better align with what is observed. Hawking has been trying to reconcile Einstein's Theory of General Relativity with the principles of modern day quantum mechanics. They often appear to be in conflict. Hawking was one of the few theoretical physicists with the intellectual horsepower to take on the challenge.

[dara]

Don't forget to bring your umbrella so you won't get showered by Chinese Spacelab lol.

[ilan]

The weather calls for space vehicle showers tonight...

China's Tiangong-1 space lab will fall from the sky on Sunday evening, according to the latest estimates from the European Space Agency, or ESA.The derelict spacecraft has been slowly falling out of its original orbit for several years. It will largely, though not entirely, burn up on reentry. (If that sounds alarming, remember that space debris falls to Earth with some regularity, and has never injured a human being.)The "re-entry prediction window" from ESA has tightened significantly, to a four-hour window centered on 1 a.m. UTC on Monday. In the continental U.S., that's Sunday evening.

From NPR 1:52 ET

[ilan]

Tiangong-1 crash: China says space station came down in Pacific Ocean (The Guardian)

Officials say the space station, which had been out of control since 2016, mostly burnt up on re-entry.

The US military appeared to confirm the re-entry with a statement from its Joint Force Space Component Command (JFSCC).