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The Moon's place in the sky



  • Registered Users Posts: 14,310 ✭✭✭✭M.T. Cranium

    The moon is full on Thursday morning while setting, and also it will occult (move in front of) Mars. The exact times of this event, should skies be clear Thursday morning, are 0455h to 0556h (Dublin), very similar times elsewhere in Ireland. The moon will be relatively high at that hour in the west-southwest moving down towards a northwesterly setting point after the occultation ends. This link provides all the details:

    I will get to see this in the evening on Dec 7th as the moon is rising between 7 p.m. and 8 p.m. ... that works out to be two hours earlier in universal time. The difference is caused by our different perspectives at event time, as I'll be to the right of the sun-earth-moon alignment directed outwards and you will be to the left of it. Therefore my line of sight requires the moon to be somewhat earlier (before the full moon alignment at 0408z) and yours requires it to be later (by roughly similar amounts). Hoping to see this but forecast is 50-50 with increasing cloud ahead of an expected snowfall on Thursday here. Your chances in Ireland may be reasonable but a fair amount of cloud will be generated by the cold air crossing warmer waters. Observers in parts of the south and west may have the better chances Thursday morning.

    Earlier that same night when the moon is crossing the transit point (due south) after midnight, you'll certainly notice how high in the sky the moon is travelling at a declination near 26N (so it's about where the Sun might appear in the sky around 21-22 June at a latitude three degrees south of your own).

  • Registered Users Posts: 21,999 ✭✭✭✭Esel

    Something I wondered about - does moonlight heat the earth at all?

    Not your ornery onager

  • Moderators, Computer Games Moderators, Technology & Internet Moderators, Help & Feedback Category Moderators Posts: 25,021 CMod ✭✭✭✭Spear

    It's incoming photons, so in principle yes. But the amount is a few thousands of what the earth receives from the Sun, so the impact is negligible.

  • Registered Users Posts: 14,310 ✭✭✭✭M.T. Cranium

    If you have breaks in the cloud tonight check out how high the full moon is riding, at its current declination of almost 27 deg. The two fairly bright stars nearby are Castor and Pollux, the twins of Gemini. Pollux is the lower one closer to the moon. Its declination is slightly more than 28 deg so it could be occulted by the Moon near its declination maximum in a year or two. I'll have a look later as it may be closer by the time I'm looking at about 06z. We have a few breaks in the overcast here, not sure if that will last to midnight though.