What does the night sky look like on Mars? • Hacker News Board

Re: What does the night sky look like on Mars?

#71

Post by dmurray » Wed, Jan 27, 2021, 9:13 AM UTC

Medox wrote: post #14

hbcondo714 wrote: post #8

> You would see two moons in that sky instead of one Any pictures of this?

There are some videos (from pictures) of eclipses, which show both: https://www.youtube.com/watch?v=M_Kn3M2ierk This one more zoomed out, but only with Phobos: https://www.youtube.com/watch?v=ViiriVhIhjE Taking into account that the Sun itself is seen smaller than on Earth, we can already imagine the view. The main problem would be that "Phobos is one of the least reflective bodies in the Solar System, with an albedo…

0.07 doesn't sound like a show stopper. The moon is 0.12, so Phobos reflects 40% less light for that reason. The sun being further away (1.5 AU) has a bigger effect due to the inverse square law - that costs 55% of the light. But the biggest effect would come from the fact that it's tiny, about 0.65% of the radius of the moon, orbiting 60x closer, which two factors combine to make it another 60% dimmer than the moon. Then there's the atmosphere which I expect to have a relatively small effect assuming good conditions on both Earth and Mars.

So overall I estimate it should be 0.6 x 0.45 x 0.4 = 0.1, or about one-tenth as bright as the moon, or apparent magnitude -10. That would make it far brighter than we see Venus or Jupiter, but makes me question the assertion in TFA that it would cast shadows - I don't expect many shadows on earth when the moon is one day old.

Re: What does the night sky look like on Mars?

#72

Post by fctorial » Wed, Jan 27, 2021, 9:19 AM UTC

Didn't we send bots with cameras to mars?

Re: What does the night sky look like on Mars?

#73

Post by Uke » Wed, Jan 27, 2021, 9:21 AM UTC

saalweachter wrote: post #53

perl4ever wrote: post #38

Earlier quoted context omitted.

Astronomers, amateur or otherwise, have been complaining about "light pollution" forever. Traditionally, it's about night-time lighting on Earth that isn't shielded from transmitting light upwards. It startled me to find (in a long ago HN thread) that people, presumably nerdy types, are not generally sympathetic to the complaints. I somehow assumed that universal lukewarm quasi-environmental feelings would mean peopl…

> ...but apparently "fuck astronomers" is a popular opinion. They know what they did. (Leap seconds.)

fun fact - mars has great time zones. No silly country borders and also had them even before we had time zones on earth https://marscalendar.com/time-zones

Re: What does the night sky look like on Mars?

#74

Post by 4gotunameagain » Wed, Jan 27, 2021, 9:34 AM UTC

fctorial wrote: post #72

Didn't we send bots with cameras to mars?

Didn't you click the article to see that it has images from them?

Re: What does the night sky look like on Mars?

#75

Post by aaron695 » Wed, Jan 27, 2021, 9:39 AM UTC

Teknoman117 wrote: post #6

Ah, yes, amateur astronomy on Mars. Something we'll not be able to do in my lifetime sadly.

> Something we'll not be able to do in my lifetime sadly.

Unless you have terminal cancer, there is a path that might allow it to happen.

Of all the things HN thinks might happen because 'optimism' this is a lousy one to chose to be mostly accurate on.

Re: What does the night sky look like on Mars?

#76

Post by yason » Wed, Jan 27, 2021, 10:14 AM UTC

tandr wrote: post #2

> Night-time temperatures can drop to -900C wait, what?

At -900 C, Kelvin is dead.

Re: What does the night sky look like on Mars?

#77

Post by throw8932894 » Wed, Jan 27, 2021, 10:44 AM UTC

yason wrote: post #76

tandr wrote: post #2

> Night-time temperatures can drop to -900C wait, what?

At -900 C, Kelvin is dead.

In 2021 lord Kelvin is definitely dead.

Re: What does the night sky look like on Mars?

#78

Post by mnw21cam » Wed, Jan 27, 2021, 11:21 AM UTC

4gotunameagain wrote: post #74

fctorial wrote: post #72

Didn't we send bots with cameras to mars?

Didn't you click the article to see that it has images from them?

I clicked on the article, and it showed me no images.

Re: What does the night sky look like on Mars?

#79

Post by mnw21cam » Wed, Jan 27, 2021, 11:25 AM UTC

temp667 wrote: post #22

Is this serious - crawling with starlink sats? At night I'm really not noticing starlink sats even on earth. What I'm noticing is MASSSIVE light pollution. For an article about looking up with the human eye at the stars, the hit on starlink sats is so weird. Starlink is probably going to be what makes internet initially possible on marks, may even be part of the mars - earth backhaul network, probably spacex will be…

From linux/net/ipv4/tcp_timer.c:

I guess we'll have to use something other than TCP to talk to the University of Mars.

Re: What does the night sky look like on Mars?

#80

Post by holografix » Wed, Jan 27, 2021, 1:47 PM UTC

throwawayboise wrote: post #65

holografix wrote: post #59

I wonder if generations of humans born and raised on Mars might start adapting their eyes to blue wave lengths!

Not unless there's some sort of natural (or artificial) selection for it.

I’m not sure why but my mind went straight to “depression”. I imagine earthlings would suffer of seasonal affective disorder from seeing a pale gray/blue sky forever and no red or yellow sun above them.

Kind of like a perpetual winter