UmbralRaptor

UmbralRaptor t1_jeghwlv wrote

Reply to Universal maps of where things actually are now by frustrated_staff

Pretty much any software that generates starcharts (eg: stellarium) will show you the actual positions of stars (as seen from earth), considering things like proper motion. That said, this is a high precision thing, so might be extremely non-obvious (Barnard's Star is only 10.3"/year).

We are currently in the process of getting high enough precision to get proper motions for nearby galaxies. Using radial velocities alone could certainly make things misleading, and a lot of large scale maps of the universe tend to prefer going by redshift instead of making additional assumptions about how the universe has expanded.

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UmbralRaptor t1_jebifl2 wrote

Reply to comment by Gumburcules in The Silver Line to Dulles is a bigger deal than I thought it would be by MrMoustachio55

Then who is it for? Why are so many stops so far away from everything? Why is it necessary to check across multiple apps (or pdfs) what the bus is so one can actually get from point A to B? Why is the "last bus problem" a constant threat meaning that you always have to be ready for a several mile walk? Especially if you're out after 4-8 pm (depending on the day of the week).

Is the goal actually to get people around?

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UmbralRaptor t1_je5qfok wrote

Reply to The Silver Line to Dulles is a bigger deal than I thought it would be by MrMoustachio55

I mean, it's nice that getting to/from IAD has gone from a 4-seat ride to a 3-seat one, but it's not world-shattering.

Edit: apparently from the downvotes a lot of people don't know how much one needs to use buses to get to/from metro stations. (or deal with several mile walks). You should try actually using the transit here.

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UmbralRaptor t1_jdxh24v wrote

Reply to Hypothetical question by jd-sutton

1 arcsecond angular resolution implies a linear resolution of 1 au at a distance of 1 parsec. We're deep within small angle approximation land, so can easily show what 0.1" gets you at varying distances:

distance resolution comment
1 ly 0.03 au Barring clever lightcurve reconstruction, you would not be able to tell that the moon exists
10 ly 0.3 au I'm unsure that you could find Earth. (I mean, JWST's coronagraph doesn't have the contrast for this, but I'm also concerned about the inner working angle)
100 ly 3 au This would be beyond the capabilities of even proposed telescopes like the HabEx starshade

FWIW, HST has a comparable angular resolution to JWST, as do some spy satellites. (notably the ones that took the image that Trump leaked)

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UmbralRaptor t1_jab7uls wrote

Reply to What do you spend per month on groceries in DC? by questionsbecause

checks notes

In 2022 my expenses included:

  • $110 on Metro/transit
  • $1509.41 on my car/driving (interestingly, insurance costs > maintenance costs > parking costs > gasoline. Though since I'm pretty sure this is amalgamating car insurance with apartment insurance...)
  • $0 on rideshare (not my thing)
  • $4154.45 on groceries (edit: this might have been 100% at Safeway)
  • $0 on alcohol (I don't drink)
  • $526.16 on eating out (albeit $131.04 of that was on a business trip)
  • $17436 on rent (1bd apt)

Note that I live alone

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