# Why was the moon so bright yesterday morning? **URL:** \ **Category:** Factual Questions\ **Created:** [January 10, 2012, 12:44am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990 "2012-01-10T00:44:43Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [January 10, 2012, 12:44am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/1 "2012-01-10T00:44:43Z")
Yesterday morning at about 07:15 I was driving home after a night shift, and the moon was very bright indeed. So bright that it would have cast visible shadows were it not for the street lights. I’m wondering why it was so bright. I know it was near full and the Earth is near perihelion, but what else was likely to have contributed? I’m in Aberdeen, Scotland, BTW ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 10, 2012, 12:46am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/2 "2012-01-10T00:46:26Z")
The full moon is always bright enough to cast visible shadows. The real question is why you noticed this just now, when you haven’t before. ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [January 10, 2012, 12:49am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/3 "2012-01-10T00:49:53Z")
> [@Chronos](#): > > The full moon is always bright enough to cast visible shadows. The real question is why you noticed this just now, when you haven’t before. I’ve generally lived in or near cities, most recently right next to Luton Airport, so there’s been plenty of atmospheric pollution, both from light and dust. ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [January 10, 2012, 1:17am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/4 "2012-01-10T01:17:11Z")
Maybe Larry Niven has some idea. 😉 ---
**Author:** ![VOW](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/vow/32/3043_2.png) [@VOW](https://boards.straightdope.com/u/VOW)\ **Post date:** [January 10, 2012, 2:40am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/5 "2012-01-10T02:40:17Z")
The Man in the Moon finally made the transition to LED? ~VOW ---
**Author:** ![brocks](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@brocks](https://boards.straightdope.com/u/brocks)\ **Post date:** [January 10, 2012, 3:03am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/6 "2012-01-10T03:03:59Z")
As you speculated, perihelion should do it. Perihelion and perigee combined should be super-bright, but the closest full moon to that for the next few years will be in 2018. But as Chronos said, every full moon casts shadows, if the atmosphere is clear. In fact, the moon on the breast of the new fallen snow gives a luster of midday to objects below. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 10, 2012, 3:21am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/7 "2012-01-10T03:21:38Z")
> [@brocks](#): > > … > the moon on the breast of the new fallen snow/ > gives a luster of midday to objects below. This is a nice line of poetry. (I am not being sarcastic.) ---
**Author:** ![brocks](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@brocks](https://boards.straightdope.com/u/brocks)\ **Post date:** [January 10, 2012, 3:57am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/8 "2012-01-10T03:57:57Z")
> [@Leo\_Bloom](#): > > This is a nice line of poetry. (I am not being sarcastic.) Thank you. I’m very proud of it, and will not dignify rumors of plagiarism with a response. ---
**Author:** ![aerodave](https://avatars.discourse-cdn.com/v4/letter/a/f08c70/32.png) [@aerodave](https://boards.straightdope.com/u/aerodave)\ **Post date:** [January 10, 2012, 5:27am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/9 "2012-01-10T05:27:20Z")
Did anyone else feel a breeze in here? ---
**Author:** ![GuanoLad](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guanolad/32/42_2.png) [@GuanoLad](https://boards.straightdope.com/u/GuanoLad)\ **Post date:** [January 10, 2012, 7:18am UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/10 "2012-01-10T07:18:14Z")
> [@brocks](#): > > Thank you. I’m very proud of it, and will not dignify rumors of plagiarism with a response. Donder und Blitzen! I like it when the moon casts a blue\* tinged light. \*Presumably for the same reason the sky is blue. ---
**Author:** ![Freddy\_the\_Pig](https://avatars.discourse-cdn.com/v4/letter/f/a587f6/32.png) [@Freddy\_the\_Pig](https://boards.straightdope.com/u/Freddy_the_Pig)\ **Post date:** [January 10, 2012, 3:14pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/11 "2012-01-10T15:14:00Z")
When one encounters a moon shadow, the correct response is to start leaping and hopping. ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [January 10, 2012, 3:19pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/12 "2012-01-10T15:19:23Z")
You know, I thought the moon was unusually bright yesterday AM, too. But I’ll chalk it upt to not having been out in a full moon for awhile, or it being cloudy during the last few. One thing to keep in mind is that moon’s position in the sky is opposite to that of the sun-- it’s high in winter and low in summer. Perhaps the winter full moon is more noticeably bright than it’s summer counterpart because how high in the sky it is. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 10, 2012, 3:22pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/13 "2012-01-10T15:22:43Z")
Did it take long to find you? ---
**Author:** ![whitetho](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whitetho/32/1059_2.png) [@whitetho](https://boards.straightdope.com/u/whitetho)\ **Post date:** [January 10, 2012, 3:23pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/14 "2012-01-10T15:23:06Z")
This morning there was a full overcast. I saw what I thought was the sun dimly shining through, then noticed the direction I was going meant is was actually the moon, so it does seem brighter than usual. ---
**Author:** ![Eve](https://avatars.discourse-cdn.com/v4/letter/e/9e8a1a/32.png) [@Eve](https://boards.straightdope.com/u/Eve)\ **Post date:** [January 10, 2012, 3:31pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/15 "2012-01-10T15:31:27Z")
“The moon? The \*sun! \*It is not moonlight now. I know it’s the \*sun \*that shines so bright.” ---
**Author:** ![John\_Mace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_mace/32/185_2.png) [@John\_Mace](https://boards.straightdope.com/u/John_Mace)\ **Post date:** [January 10, 2012, 3:33pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/16 "2012-01-10T15:33:50Z")
Arise, fair sun, and kill the envious moon, Who is already sick and pale with grief. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [January 10, 2012, 3:41pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/17 "2012-01-10T15:41:24Z")
I also noticed how exceptionally bright the moon seemed on Sunday night. There was quite a lot of cloud, so I could only just make out the outline of the moon, and yet it was bright enough to read by at midnight. (I’m in England.) ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [January 10, 2012, 4:32pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/18 "2012-01-10T16:32:35Z")
The variation of the Moon’s brightness due to the its distance from the Sun at perihelion vs. aphelion should only be about 7%, and I’m a little doubtful that such a small effect would be noticeable. For comparison, the variation in brightness due to the Moon’s perigee vs. apogee would be about 25%; the Moon’s orbit around the Earth is much more eccentric than the Earth’s about the Sun. My guess is that **John Mace** ’s explanation is the closest to the truth. (Unless a massive solar flare wiped out the day side of the Earth, but then the storms due to the superheated steam would probably have reached you by now) ---
**Author:** ![brocks](https://avatars.discourse-cdn.com/v4/letter/b/7feea3/32.png) [@brocks](https://boards.straightdope.com/u/brocks)\ **Post date:** [January 10, 2012, 4:51pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/19 "2012-01-10T16:51:01Z")
> [@MikeS](#): > > The variation of the Moon’s brightness due to the its distance from the Sun at perihelion vs. aphelion should only be about 7%, and I’m a little doubtful that such a small effect would be noticeable. For comparison, the variation in brightness due to the Moon’s perigee vs. apogee would be about 25%; the Moon’s orbit around the Earth is much more eccentric than the Earth’s about the Sun. My guess is that **John Mace** ’s explanation is the closest to the truth. If the OP saw a nearly full moon at 0715, it wouldn’t have been very high in the sky. I’m guessing some combination of perihelion, clear air, and maybe a small solar flare. ---
**Author:** ![Malden\_Capell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/malden_capell/32/5274_2.png) [@Malden\_Capell](https://boards.straightdope.com/u/Malden_Capell)\ **Post date:** [January 10, 2012, 4:52pm UTC](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990/20 "2012-01-10T16:52:10Z")
> [@MikeS](#): > > (Unless a massive solar flare wiped out the day side of the Earth, but then the storms due to the superheated steam would probably have reached you by now) I saw that Outer Limits episode. [Next page](https://boards.straightdope.com/t/why-was-the-moon-so-bright-yesterday-morning/608990.md?page=2)