APOD: Love and War by Moonlight (2021 Jul 16)

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APOD Robot
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APOD: Love and War by Moonlight (2021 Jul 16)

Post by APOD Robot » Fri Jul 16, 2021 4:06 am

Image Love and War by Moonlight

Explanation: Venus, named for the Roman goddess of love, and Mars, the war god's namesake, come together by moonlight in this serene skyview, recorded on July 11 from Lualaba province, Democratic Republic of Congo, planet Earth. Taken in the western twilight sky shortly after sunset the exposure also records earthshine illuminating the otherwise dark surface of the young crescent Moon. Of course the Moon has moved on. Venus still shines in the west though as the evening star, third brightest object in Earth's sky, after the Sun and the Moon itself. Seen here above a brilliant Venus, Mars moved even closer to the brighter planet and by July 13 could be seen only about a Moon's width away. Mars has since slowly wandered away from much brighter Venus in the twilight, but both are sliding toward bright star Regulus. Alpha star of the constellation Leo, Regulus lies off the top of this frame and anticipates a visit from Venus and then Mars in twilight skies of the coming days.

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VictorBorun
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by VictorBorun » Fri Jul 16, 2021 5:29 am

how come that Mars is double-exposed like all the stars but one?
Love and War by Moonlight-.jpg
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De58te
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by De58te » Fri Jul 16, 2021 11:17 am

VictorBorun wrote:
Fri Jul 16, 2021 5:29 am
how come that Mars is double-exposed like all the stars but one?
The photographer had slightly shaky hands? Maybe that one light is a distant night plane heading in the different direction which by chance aligned up with the movement of the camera?

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orin stepanek
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by orin stepanek » Fri Jul 16, 2021 11:49 am

2021Jul11MarsVenusMoon_ShiHuan.jpg
Beautiful photo! Kudos to Shi Huan!
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by johnnydeep » Fri Jul 16, 2021 3:29 pm

VictorBorun wrote:
Fri Jul 16, 2021 5:29 am
how come that Mars is double-exposed like all the stars but one?
Love and War by Moonlight-.jpg
Well, you get an A for being observant, that's for sure! Here's something else in the same "one of these things is not like the others" category:

What's This Smear.JPG
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by saturno2 » Fri Jul 16, 2021 7:50 pm

Interesting image

heehaw

Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by heehaw » Fri Jul 16, 2021 8:43 pm

Inspired me to dig this out: Transit of EARTH: https://henry.pha.jhu.edu/Transit.of.Earth.pdf

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alter-ego
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by alter-ego » Sat Jul 17, 2021 4:59 am

johnnydeep wrote:
Fri Jul 16, 2021 3:29 pm
VictorBorun wrote:
Fri Jul 16, 2021 5:29 am
how come that Mars is double-exposed like all the stars but one?
Love and War by Moonlight-.jpg
Well, you get an A for being observant, that's for sure! Here's something else in the same "one of these things is not like the others" category:


What's This Smear.JPG
Good catches of those images. I've done some quick visual estimates and simple calculations that support your faint streak could be a satellite.
→ I estimate the image exposure time is close to 10 seconds, give or take
→ I estimate the streak length ~0.12°
→ I estimate the limiting magnitude at this elevation ~8.5 magnitude

For this to be a satellite, it must be in a higher orbit than LEO. The streak length is too short for an LEO satellite (LEO streak of the order 10°)
→ A very close candidate is a GPS satellite at 20,200km, traveling at 13,900km/hr. In 10 seconds, the calculated streak length ~ 0.11°

I've not searched for any satellites that might be visible from this region or if any of these mid-orbit satellites are visible, and I don't know the expected magnitude. It may be coincidence, but a satellite is a logical candidate.

As far as the other anomalous spots go, they be artifacts from the camera, but I'm guessing they are not actual light sources in the sky.
A pessimist is nothing more than an experienced optimist

VictorBorun
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Re: APOD: Love and War by Moonlight (2021 Jul 16)

Post by VictorBorun » Sat Jul 17, 2021 6:37 am

alter-ego wrote:
Sat Jul 17, 2021 4:59 am
Good catches of those images. I've done some quick visual estimates and simple calculations that support your faint streak could be a satellite.
→ I estimate the image exposure time is close to 10 seconds, give or take
→ I estimate the streak length ~0.12°
→ I estimate the limiting magnitude at this elevation ~8.5 magnitude

For this to be a satellite, it must be in a higher orbit than LEO. The streak length is too short for an LEO satellite (LEO streak of the order 10°)
→ A very close candidate is a GPS satellite at 20,200km, traveling at 13,900km/hr. In 10 seconds, the calculated streak length ~ 0.11°

I've not searched for any satellites that might be visible from this region or if any of these mid-orbit satellites are visible, and I don't know the expected magnitude. It may be coincidence, but a satellite is a logical candidate.

As far as the other anomalous spots go, they be artifacts from the camera, but I'm guessing they are not actual light sources in the sky.
wow high orbit satellites are visible for a camera!
3-minute exposure gets a row of geosychronous ones: