Moon News

[Posted by Chuck Almdale]

At our Malibu Lagoon field trip yesterday, Paula jumped into the introductory announcements with some news of her own: the new moon was currently at its closest to the earth in 990 years. This was news to me, so I checked a few sources. Here’s the lowdown.

A few fundamentals:

The moon’s orbit around the earth is an oval; so is the earth’s orbit around the sun.
The moon’s closest point to the earth is the perigee, farthest is the apogee.
The earth’s closest point to the sun is the perihelion, farthest is the aphelion.

The moon’s perigee can occur at any point in its phase cycle, so it rarely occurs when the moon is either full or new.

The earth’s perihelion slowly shifts 1 day every 58 years. It’s currently Jan 4/5. King tides fall at new moon closest to the perihelion, so our king tide season will slowly shift forward. In 6340, perihelion will fall on the March equinox (currently approximately Mar 21).

A full moon at or near perigee is a supermoon.
When the moon’s perigee occurs close to or at the earth’s perihelion, the annual perihelion-caused King Tides are very high.

Here’s some articles on the recent “super-new-moon,” followed by some tidal info.

The new moon is the closest in nearly 1,000 years tonight
Space.com | Stephanie Waldek | 21 Jan 2023
It’s the closest new moon to Earth since the year 1030. At 3:54 p.m. EST (2054 GMT), the moon will be exactly 221,561 miles (356,568 km) away from our planet, according to Timeanddate.com (opens in new tab), which sifted through data from NASA’s Jet Propulsion Laboratory to determine the distances of every Earth-moon distance for hundreds of years. 

On Saturday … Closest new moon in 1,337 years
EarthSky | Graham Jones | 19 Jan 2023

Why The Moon Is Suddenly Closer To Earth Than For 992 Years—And What It Means
Forbes | Jamie Carter 18 Jan 2023
On Saturday, January 21, 2023, the New Moon will be precisely 221,561 miles/356,568 km from Earth. As reported by Timeanddate.com, that’s the closest it will come to our planet since the year 1030—a time of the Crusades, the Norman Conquest of Britain and early Vikings settlements in North America, a century ironically sometimes called the “Dark Ages.” This “ultimate supermoon” also signals the beginning of Chinese Lunar New Year and comes during a rare conjunction between Venus and Saturn that will be best viewed just after sunset in the southwest on Sunday, January 22, 2022.

Why is the Moon suddenly so close?

Tide table below for period: 30 Dec 2022 to 28 Jan 2023
Full Moon: 6 Jan 2023 6:09 PM High tide: 5.78 feet on both 5 Jan 7:38am, 6 Jan 8:11am
New Moon: 21 Jan 2023 12:53 PM High tide: 6.84 feet 21 Jan 8:11am
The new moon high tide was 16 days farther from perihelion than was full moon high tide, yet was more than a foot higher. Thus perigee + new moon outweighed perihelion + full moon.