Total Lunar Eclipse - January 20 & 21, 2019

Equipment: 6" Takahashi TOA-150 apochromatic refractor on a Takahashi NJP Temma 2 mount, Nikon D810A

Exposure: 700+ exposures every 30 seconds, 1/1000 sec to 6 sec, ISO 100

Location: Grapevine, Texas.

This linear composition shows the eclipse sequence, moving right to left. This seems counterintuitive…while the moon moves left to right (east to west) from our perspective in Texas, the shadow of the earth actually catches up to the moon from the left side, eclipses it, and exits out of the moon after about 6 hours, speeding on ahead.

What many do not realize is that there are two aspects to the shadow, a penumbra, where sunlight begins to hide the lunar surface (note the dimming of the lunar limb once it enters the penumbral ring), and an umbra, when sunlight is completely blocked on the lunar surface.

Both the penumbral and umbral rings are shown here to scale. The actual lunar size of approximately 30 arc minutes is demonstrated by the smaller lunar images shown here.

To become a “total” eclipse, the moon must enter the umbral ring entirely. When it does, it takes on a red hue, caused by the scattering of blue light through earth’s own atmosphere.

Some lunar eclipse “totalities” last longer than others. Here in Grapevine, Texas, the moon barely entered the umbral ring, which is why even at totality (blown up and centered in this composition) the northern rim of the moon has a slight brightening to it.