Moon Question of the Day

Why is there a crescent Moon cutout in outhouse doors?

We don't know whether the crescent Moon was the standard cutout in every outhouse door in the country, but it's certainly the embellishment of choice for artists and illustrators. Such an opening may have been chosen because (1) it provided some ventilation and illumination and (2) it afforded a modicum of privacy for the occupant.

Last 7 Days

When does a new Moon rise?

The new Moon always rises at sunrise. The full Moon always rises at sunset.

Exactly how long is a lunar month?

The Moon's synodic period (the length of a lunar month) is 29.53059 days -- or 29 days, 12 hours, 44 minutes, and 2.8 seconds.

On December 26, 1978, the Moon had a star resting on its tip. What was this called and how often does it happen?

In the morning hours of December 26, 1978, Venus was totally obscured by the Moon, depending upon where you were standing. From some angles, it appeared the planet was resting on the Moon. Such a phenomena is called a "lunar occultation."

In south Texas, I saw the largest ring around the Moon I've ever seen. Why so big and does it predict weather?

The ring around the Moon (and sometimes the Sun) is called a halo. The most common halos are caused by hexagonal ice prisms where the light enters and exits through one of the side faces and the halos have a diameter of 44 degrees. A quite rare form of halo is produced by cubic ice crystal or by hexagonal ice prisms where the light goes through the end faces of the prism and this halo has an diameter of 92 degrees. I am sure you saw this 92 degree halo in that clear Texan night-a rare event. In 60 years of observing the nigh sky, I have only seen this twice. As far as I know, it has no weather prognosticating indications.

What were the Blue Moons during the Civil War years (1861-1865)?

A Blue Moon is the second full Moon in a month with two full Moons. Since the time between two full Moons (the synodic month) is 29.530588 mean solar days (29 days, 12 hours, 44 minutes, 3 seconds), this is somewhat shorter than all calendar months except February. A Blue Moon will occur on average every two or three years. During the Civil War, from April 12, 1861 to June 2, 1865, only one Blue Moon occurred and that was in July of 1863.

Can you please tell me where I should go to see the "horns" of the Moon pointing up?

Around 18 to 28 degrees north latitude, the horns of the Moon at times point directly up. This happens just after sunset in the west, near the horizon, for a waxing Moon and just before sunrise in the east, near the horizon, for a waning moon. The same is true at around 18 to 28 degrees south latitude--just exchange east and west. A beautiful picture of the Moon with its horns pointing upward (but not straight up) is visible over a much wider area. In the United States, southern Florida is a great place to see this.

Exactly how long is a lunar month?

The Moon's synodic period (the length of a lunar month) is 29.53059 days -- or 29 days, 12 hours, 44 minutes, and 2.8 seconds.

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