Observed magnitudes of Qianfan spacecraft range from 4 when they are near zenith to 8 when low in the sky.
Since this is the first run of the Qianfan satellite constellation, the most appropriate comparison would be to Starlink’s original satellites. As you can see below, the notion that China’s satellites are “significantly brighter than those of Western systems” is a inaccurate.
The Original spacecrafts have a relatively flat phase function, so they are comparatively bright over a wide range of phase angle. […] the characteristic magnitudes are: 4.7 (Original) […]
The mean apparent magnitude of Starlink Mini Direct-To-Cell (DTC) satellites is 4.62 while the mean of magnitudes adjusted to a uniform distance of 1000 km is 5.50.
Clearly, even the newest Starlink satellites are well above the magnitude 7 limit astronomers recommend for satellite brightness.
Barnard b [2], as the newly discovered exoplanet is called, is twenty times closer to Barnard’s star than Mercury is to the Sun. It orbits its star in 3.15 Earth days and has a surface temperature around 125 °C. “Barnard b is one of the lowest-mass exoplanets known and one of the few known with a mass less than that of Earth. But the planet is too close to the host star, closer than the habitable zone,” explains González Hernández. “Even if the star is about 2500 degrees cooler than our Sun, it is too hot there to maintain liquid water on the surface.”
Aww that’s cute. Barnard’s star has kind of an interesting history of exoplanet claims that were sadly ruled out after further examination. Great to hear we finally have good evidence.
After more than a century of speculation, data seem to confirm that Betelgeuse (the brightest star in the Orion constellation, shown here) has a much smaller star as an orbital companion.
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Two independent studies found evidence of a star about the same mass as the sun, orbiting Betelgeuse about once every 2,100 days.
What if dark matter is some form of black hole or exotic ultra dense material made entirely out of the missing antimatter, which for whatever reason doesn’t otherwise interact with electromagnetism? 2 birds, 1 stone.
You don’t need the event horizon, you just need local gravity around 1G. For the masses described in the article, that radius is from hundreds of meters to 10s of kilometers.
Which still wouldn't do what you suggest. The mass is the same, so it has the same effect from a distance. Unless by "eat earth" you meant it would take in dirt until it suck to the core, still about the same mass.
Yes, it would just be surprising because, gravity should make them not be evenly distributed.
The whole thing with dark matter is that it’s this magic stuff that causes gravity but isn’t affected by it, which… is not how gravity normally works.
Though there is still room for it, we just need a better framework other than “I added 3 and 5 and got 12, so obviously I must mean to add 3 and 5 and 4 too”.
Then it should also coelescce, particularly since it doesn’t have the em force to keep it repelled, the universe should be dominated by massive dark matter black holes.
Yes, there’s math that explains part of the distribution, but also there is 0 force opposing any collapse we’d have a lot more neutron stars and other degenerate matter catalyzed by dark matter.
We have hypotheses like this when our observations don’t make sense and we need to explain them, it’s definitely a possibility but we still have room to understand the large scale physics at play.
You don’t need a force to prevent collapse if there’s no drag force to slow things down. It would actually be almost impossible for a cloud of dark matter to collapse since any individual particle has momentum and no way to slow down, so they’ll all be in some sort of mutual orbit
I’m guessing you’ve seen as many lorentz attractor simulations as I have, what always happens is something like tidal effects or angular momentum means 90% slow down while a few particles get shot out of hell at ludicrous speed.
The effect is similar to drag, and is basically how we get entropy even without em effects.
If dark matter is fully explained by such black holes, their most likely mass, according to some theories, would range from 10^17^ to 10^23^ grams—or about that of a large asteroid.
In case this doesn’t tell you a lot, 10^17^g is half the weight of Mount Everest, and 10^23^g is 4x the weight of the Antarctic ice shield.
The earth is estimated to “weigh” 13,170,000,000,000,000,000,000,000 pounds. (That is weird when you think about it. The weight of the earth being based on what something weighs on earth, I mean.)
Mt. Everest is only about 357,000,000,000,000 pounds and is just a tiny fraction of the mass of the earth.
So. My point is that we need a better way to portray scale of things in the universe. AUs work to a point but then we have to quickly move to parsecs. Parsecs quickly give way to light years. (Or vice-versa, depending on how you visualize things better.) Light years kinda work, but only for between 14-26 billion years. Even after all of that, I can hardly still fathom the size of Mt. Everest. (This was a rant, but not an angry rant.)
Weight in pounds isn’t the right unit here. Weight varies depending on the strength of the gravitational field you’re in, whereas mass does not. A kilogram here on earth weighs 2.2lbs but on the moon it only weighs 0.36lbs.
In the English Engineering System, the unit of mass is 1 pound mass (lbm), and is equivalent to the amount of matter that weighs 1lb at 1G. I won’t argue that EES is a good system, but it does at least have a kludged unit for mass. It has an equally kludged unit for force, too, called pounds force (lbf).
I cannot fathom the size of anything on an astronomical scale. I have seen the videos that zoom out and show Earth at scale with the Sun and then the Sun at scale with other stars. No matter how many times I view the facts it will be incomprehensibly large.
Would a regular asteroid be able to wobble the earth as described in this article? Or is it just black holes that should do so?
I seem to remember reading that primordial black holes weren’t yet a proven phenomenon and I have trouble imagining them myself. Wouldn’t they have hawking radiation too which we would be able to detect?
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