(Phillip Gabero) wrote in message
om:

Hi group!

Let's say

- there was a habitable planet around Alpha Centauri-A
- at 1,2 AU
- A & B are at closest approach (11,2 AU)
- B is at opposition, getting the planet as close as
10 AU to B
- A is 90° below the horizon, B is 90° above the horizon

At 10 AU Alpha Centauri-B's apparent magnitude is -20,9,
which makes it 223 times dimmer than our sun.

My question now is what are the light levels like at that
time? I mean, we all know what light levels a full moon
produces, but what is "223 times dimmer than our sun" like?

Well, maybe like night in a modern city which has lots of street lights.

I witnessed a partial eclipse back in 1999, when the moon
covered 99% of the sun where I live. With the sun at ~55°
above the horizon it was still pretty bright (clear skies).

Compared to that light levels on the planet around Alpha
Centauri A would still be 2 times dimmer (magnitude-light levels?),
but I guess this means "no night" during that time of the
year nevertheless.

What do you think (and feel free to correct any mistakes/wrong
assumptions)?

Could there be periods on such a planet when none of the Alpha Centauri
stars is visible? If yes then it would look very much like here on Earth.