The Astronomy Thread

[GeoModder]

Humanity should have owned blue skin xenos, instead we got some Disney tier ending.

Fighting a whole world 4,35 light years away from home? I don't think so.

Should have nuked them from orbit, them and their trees.

There's literally a world of difference between fighting a world and nuke it.

[Arioch]

[Arioch]

Observing a star in a tight orbit around the Sagittarius A* supermassive black hole at the center of our galaxy to check General Relativity's non-Newtonian prediction.



At periapsis, the star is at a distance of ~1337 AU and moving at 3% lightspeed. o_O

[icekatze]

hi hi

It's kind of funny how they're hedging their bets, "center of the milky way where we suspect there is a black hole."

[Arioch]

It's kind of funny how they're hedging their bets, "center of the milky way where we suspect there is a black hole."

I noticed that, but I think it's appropriate scientific language, since there's no way to directly verify for 100% sure that the thing at Sag A* is a black hole. Everything we know says that's the only thing it could be, but everything we know could be wrong.

Frankly I find it refreshing to hear a scientist use that kind of language... it seems to me there are too many talking about things like string theory or parallel universes as if they were established fact.

[Krulle]

[...] the star is at a distance of ~1337 AU [...]

How 1337 of the star.
(or the engineer having done the calculations)

[icekatze]

hi hi

Frankly I find it refreshing to hear a scientist use that kind of language... it seems to me there are too many talking about things like string theory or parallel universes as if they were established fact.

I suppose it depends on who you're talking to. Definitely good for accuracy, and I've definitely had heated arguments in support such distinctions being important.

I guess I'm used to looking at it from a legal perspective, where lawyers get away with tricking juries into dismissing evidence all the time because they know the science experts have to say "I'm not 100% sure," or else they'll perjure themselves.

[Arioch]

An interesting map of the local neighborhood out to 10 parsecs (32.6 light years), based on Gaia mission data, including known exoplanets.

https://gruze.org/galaxymap/10pc/

[icekatze]

hi hi

An interesting map of the local neighborhood out to 10 parsecs (32.6 light years), based on Gaia mission data, including known exoplanets.

https://gruze.org/galaxymap/10pc/

Today I learned what a Stromgren Sphere was.

Comparing this to the local bubble map, the Loroi and Umiak really are a long ways away. Aldebaran isn't even close enough to be on the map here.

[Arioch]

32 ly vs. 815 ly

[GeoModder]

The declination of the Alpha Centauri system seems wrong on that map. They list it within the ecliptic plane of the map, like Sirius and Procyon.
And good heavens, it took me a while to find Tau Ceti. I'm so used to look for yellow-colored dots, and its been shown as a K class star!

[Arioch]

An interesting simulation of star formation within a molecular cloud. Of particular interest are the polar jets from particularly massive protostars.

[jterlecki]

https://www.technologyreview.com/2021/0 ... xoplanets/

Seems that 1,700 stars have been in position to detect life on Earth over the last 5,000 years. Perhaps something for Arioch to consider in his master plan!

[jterlecki]

https://phys.org/news/2021-06-black-hol ... -mass.html

Interesting - might be a large concentration of dark matter in the center of our galaxy and not a super massive blackhole.

[dragoongfa]

https://www.technologyreview.com/2021/0 ... xoplanets/

Seems that 1,700 stars have been in position to detect life on Earth over the last 5,000 years. Perhaps something for Arioch to consider in his master plan!

The radiowave's angle has long been cut down due to the way radio waves disperse over time and distance; a few light years away from Earth it would be extremely hard to differentiate between Earth's signals and background radiation.

Detecting the subtle differences of light that passes through an atmosphere in order to determine the possible composition of said atmosphere, that's more robust but I think that there is too much room for error from false positives. We cannot yet truly model the behavior of our own atmosphere (if we did we would have been able to properly predict the weather) and scientists have trouble understanding how the composition of Mars's atmosphere works within itself:

https://www.nasa.gov/feature/goddard/20 ... one-oxygen

There is too much we don't know about the cosmos yet to properly discern habitable planets from such distances; the workings and compositions of an atmosphere are far too complex to predict and analyze without lengthy and up close study. To predict if a planet is habitable just from light's interaction with an atmosphere we are unable to study?

I wouldn't put my money in any such 'discoveries' being accurate.

[Gudo]

There is too much we don't know about the cosmos yet to properly discern habitable planets from such distances... I wouldn't put my money in any such 'discoveries' being accurate.

TL10 civs would certainly have access to large space based telescopes, as well as exoplanet discovery techniques more sophisticated than we currently possess. While I would not expect either of the major combatants to have discerned that Earth is actually inhabited, I would expect both to have cataloged the planet already, including the fact that the planet lies within the star's habitual zone and has gravity that's compatible with Loroi biology. Whether or not either the Union or Hierarchy are in a position to conduct exoplanetary atmospheric spectroscopy would likely boil down to a "needs of the story" decision. IRL humans have already detected and identified atmospheric gasses around rocky exoplanets. A TL10 civ capable of conducting such spectroscopy would certainly detect atmospheric oxygen and, due to the instability of the molecule, deduce that the planet almost certainly harbors life.

Regardless, my expectation would be that once Union astronomers receive the location of Earth, they should find it's already in their catalogs marked as either potentially habitable or potentially inhabited. My own speculation would be that at the very least the Hierarchy is not in a position to conduct atmospheric spectroscopy observations on the Earth. If they were able to do so, they would notice the planet's mass, orbit, and atmosphere are all compatible with their enemies' biology. And, given Terran space's strategic position, dispatch of a scout would be prudent. Within a few years of contact with the Orgus, Terrans were able to develop, build, and dispatch scouts capable of reaching disputed space. Surely the Hierarchy, already in possession of capable craft, would've been able to dispatch an expedition within 25 years of the war's start if not before.

[jterlecki]

Well, I know we have detected water on a potential super-Earth 110 light years and we are still able to receive from a 20W emitter at a distance of around 130AU. If I recall correctly, the Earth has the distinct feat if being 'louder' than the Sun in the RF spectrum.

Other species might have been aware of the existence of Earth without necessarily knowing about humanity, especially if they observed our world before the 1900s.

It was just some food for thought however.

[Ithekro]

At 200 or so light years out I wonder if they would spot our little world, or if they would just pickup the four larger gas giants and not the inner planets?

[jterlecki]

Kepler-37b is Moon sized and 215 l.y away.

[GeoModder]

I reckon there would be less of a need for 'sufficiently advanced' exoplanetary observation techniques once you have mastered FTL travel...
Simply sent a survey vessel instead of watching old photons.