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APOD: 2019 January 17 - Cabin Under the Stars
Explanation: Gocka's, a family nickname for the mountain cabin, and a wooden sled from a generation past stand quietly under the stars. The single exposure image was taken on January 6 from Tanndalen Sweden to evoke a simple visual experience of the dark mountain skies. A pale band of starlight along the Milky Way sweeps through the scene. At the foot of Orion the Hunter, bright star Rigel shines just above the old kicksled's handrail. Capella, alpha star of Auriga the celestial charioteer, is the brightest star at the top of the frame. In fact, the familiar stars of the winter hexagon and the Pleiades star cluster can all be found in this beautiful skyscape from a northern winter night.
astronomy  photography  nature  APOD 
4 hours ago by rgl7194
Why is the night sky dark?
The mystery of the dark sky is solved by the fact that this history has a beginning—a time before stars and galaxies. Many cosmologists think the universe started out as a very small point, and then started inflating like a balloon in an event called the Big Bang. If you look deep enough, you can see so far back in time that you get close to the Big Bang. “You just run out of stars,” Kinney says. “And you run out of stars, in the grand scheme of things, relatively quickly.”
science  astronomy 
11 hours ago by terry
[1809.05128] Nuclear Processes in Other Universes: Varying the Strength of the Weak Force
Motivated by the possibility that the laws of physics could be different in other regions of space-time, we consider nuclear processes in universes where the weak interaction is either stronger or weaker than observed....

We then consider stellar structure and evolution for the different nuclear compositions resulting from BBN, a wide range of weak force strengths, and the full range of stellar masses for a given universe. We delineate the range of this parameter space that supports working stars, along with a determination of the dominant nuclear reactions over the different regimes....

Although stars in these universes are somewhat different, they have comparable surface temperatures, luminosities, radii, and lifetimes, so that a wide range of such universes remain potentially habitable.
astronomy  physics  multiverse  anthropic_principle 
11 hours ago by PeterErwin
Have Aliens found us? An Interview with the Harvard Astronomer Avi Loeb About the Mysterious Interstellar Object ‘Oumuamua | The New Yorker
Isaac Chotiner talks to Loeb, who thinks that the mysterious object dubbed ‘Oumuamua is an alien artefact:
<p>the evidence in this particular case is that there are six peculiar facts. And one of these facts is that it deviated from an orbit shaped by gravity while not showing any of the telltale signs of cometary outgassing activity. So we don’t see the gas around it, we don’t see the cometary tail. It has an extreme shape that we have never seen before in either asteroids or comets. We know that we couldn’t detect any heat from it and that it’s much more shiny, by a factor of ten, than a typical asteroid or comet. All of these are facts. I am following the facts.

Last year, I wrote a paper about cosmology where there was an unusual result, which showed that perhaps the gas in the universe was much colder than we expected. And so we postulated that maybe dark matter has some property that makes the gas cooler. And nobody cares, nobody is worried about it, no one says it is not science. Everyone says that is mainstream—to consider dark matter, a substance we have never seen. That’s completely fine. It doesn’t bother anyone.

But when you mention the possibility that there could be equipment out there that is coming from another civilization—which, to my mind, is much less speculative, because we have already sent things into space—then that is regarded as unscientific…

…Given the data that we have, I am putting this on the table, and it bothers people to even think about that, just like it bothered the Church in the days of Galileo to even think about the possibility that the Earth moves around the sun. Prejudice is based on experience in the past. The problem is that it prevents you from making discoveries. If you put the probability at zero per cent of an object coming into the solar system, you would never find it!</p>

Weirdly compelling. If it comes back... everyone hide.
science  astronomy  space  alien  Oumuamua 
21 hours ago by charlesarthur
Have Aliens Found Us? An Interview with the Harvard Astronomer Avi Loeb About the Mysterious Interstellar Object ‘Oumuamua | The New Yorker
Isaac Chotiner interviews Avi Loeb, the chair of Harvard’s astronomy department, about the interstellar object ‘Oumuamua and the possibility that it was sent by an extraterrestrial civilization.
astronomy  extraterrestrials  science  space  oumuamua  loeb  interstellar  object  asteroid  visitor 
yesterday by xer0x
Astroquery — astroquery v0.3.10.dev277
Astroquery is a set of tools for querying astronomical web forms and databases.

There are two other packages with complimentary functionality as Astroquery: pyvo is an Astropy affiliated package, and Simple-Cone-Search-Creator to generate a cone search service complying with the IVOA standard. They are more oriented to general virtual observatory discovery and queries, whereas Astroquery has web service specific interfaces.
astroquery  astropy  astronomy  python 
2 days ago by bezthomas
This Solar System Photo Was Shot From a Photographer's Backyard
Check out this family portrait of our solar system. It’s a composite photo created by a single astrophotographer who photographed the planets from his own backyard in Sacramento, California.
Photographer Andrew McCarthy shot the individual photos with a Sony a7 II camera, Canon 60D, ZWO ASI224MC color astronomy camera, Orion XT10 telescope, Meade 2120 telescope, and Skywatcher EQ6-R Pro equatorial mount.
The background Milky Way photo was shot using the Meade telescope with a Canon 60D and 28-80mm lens (at 28mm). It’s a single 2-minute exposure at f/9 and ISO 3200.
Venus, Mars, Saturn, and Jupiter were captured with the Orion telescope and ZWO camera using 8,000 to 10,000 frames each that were then stacked in Autostakkert. Uranus was shot with the Orion, Skywatcher, and Sony a7 II using a single 30-second exposure at ISO 6400.
The ISS was shot using the Orion and ZWO with 25,000 frames captured (with 25 handpicked frames aligned and stacked). Comet 46p/Wirtanen was shot with the Orion, Skywatcher, and Sony a7 II with 60 separate 30-second exposures at ISO 6400.
The Moon was captured with the Orion, Skywatcher, and ZWO with 1,000 frames. The Sun was shot with the Orion, Skywatcher, and Sony a7 II as a single 1/200s exposure at ISO 50.
Once he had all the individual photos he needed, McCarthy arranged the objects over the Milky Way background using Photoshop. Here’s a closer look at the composite photo that resulted...
photography  astronomy 
2 days ago by rgl7194
Another Day, Another Exoplanet: NASA’s TESS Keeps Counting More - The New York Times
NASA’s new planet-hunting machine, the Transiting Exoplanet Survey Satellite, or TESS, is racking up scores of alien worlds.

Less than a quarter of the way through a two-year search for nearby Earthlike worlds, TESS has already discovered 203 possible planets
astronomy  science 
3 days ago by noiseguy

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