Spectacular Show Expected From Tonight’s Lunar Eclipse

The first total eclipse of the moon in two years and what many are predicting will be the most spectacular of the past decade will begin tonight at twilight.

A total lunar eclipse occurs when the sun, Earth and moon form a straight line in space and the moon passes through the Earth’s shadow. This can happen only when the moon is full, as it is tonight.

The moon will rise at 4:59 this afternoon, coincidentally the same time as the sun sets. The moon will begin to move into the outer edge of the Earth’s shadow (the penumbra) at 6:03 p.m., at which time the moon will be about 11 degrees high in the east-northeast sky. Because the moon will be so bright in the winter sky, however, the darkening will probably not be visible to the naked eye for at least another half an hour.

To help see this early stage, some astronomers recommend wearing dark glasses or looking at the moon’s reflection on a windowpane. It also can be more easily seen if the moon’s image is projected onto white paper with a telescope.

At 7:01 p.m., the moon will begin to enter the darker, inner portion of the Earth’s shadow (the umbra), and the lower left edge of the moon will darken dramatically within a few minutes.

During the eclipse, the leading edge of the umbra’s brick-red interior could appear gun-metal blue, and the much brighter penumbra next to it a pale green or straw color. These colors can be seen more readily with the aid of binoculars.

At 8:05, the eclipse will be total, and the totality will last for one hour and 17 minutes. By 11 p.m., the eclipse will be effectively over.

Although the moon will be in the Earth’s shadow. it still will be illuminated by light that filters through the Earth’s atmosphere and is bent toward the moon. This gives the eclipsed moon its characteristic dark red color.

The moon should be a little brighter than it has been during recent eclipses because the Earth’s atmosphere has finally cleansed itself of any lingering dust and aerosols from the 1991 eruption of Mt. Pinatubo in the Philippines. Those aerosols, which reduced passage of light through the Earth’s atmosphere, have dimmed every eclipse occurring since then and have altered the apparent color of the moon during totality.

The next eclipse visible from the West Coast will occur on July 16.

For further information about the eclipse, visit: https://www.skypub.com and https://www.GriffithObservatory.org.

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Tonight’s Total Lunar Eclipse

11:24 p.m.: Moon leaves penumbra

10:25 p.m.: Moon leaves umbra

9:22 p.m.: Total eclipse ends

8:05 p.m.: Total eclipse begins

7:01 p.m.: Moon enters umbra

6:03 p.m.: Eclipse begins as moon enters penumbra

Source: Sky & Telescope magazine, American Heritage Dictionary