Lunar Eclipse on Sunday

[update: changed the time of mid-eclipse to 2:47 UT from 2:48 UT. thanks to Joe Stieber for catching the error. the one minute difference doesn’t change the rest of the article.]

Sunday evening will see the last of the recent tetrad of lunar eclipses for observers in the Americas. The eclipse will occur in the morning for observers in Europe, Africa, and western Asia. This eclipse has been hyped a bit more than usual due to the Moon being a ‘Super Moon’. What that means is the Moon is at the close part of its orbit to Earth and appears a little bit larger than usual. Regardless, all total lunar eclipses are worth seeing and this one will be very nice for western US observers as it will be located low on the horizons making for some nice views. Occurring during the early evening also means we don’t have to be up at weird hours of the night to see this one. This is especially convenient for showing the kids.

The Moon will enter the penumbra of Earth’s shadow at 00:12 UT though most observers will have a difficult time noticing any darkening of the Moon until around ~00:40 UT (8:40 pm EDT, 7:40 pm CDT). At that time the Moon will be below the horizon for Tucson and most observers in the Mountain and Pacific time zones.  The Moon enters the umbra of Earth’s shadow and really starts to get dark at 1:07 UT (9:07 pm EDT, 8:07 pm MDT, 7:07 pm MDT). At Tucson the Moon rises at 1:09 UT (6:09 pm PDT) only 1 minute after the start of the partial eclipse and 7 minutes before sunset. As the Moon gets higher and the sky gets darker it will become easier to see even as Earth’s shadow takes a bigger and bigger bit out of it.

The total phase of the eclipse begins at 2:11 UT (10:11 pm EDT, 9:11 pm CDT, 8:11 pm MDT, 7:11 pm PDT). The middle of the eclipse and the time when the Moon should appear darkest occurs at 2:47 UT (10:47 pm EDT, 9:47 pm CDT, 8:47 pm MDT, 7:47 pm PDT. Totality ends at 3:23 UT (11:23 pm EDT, 10:23 pm CDT, 9:23 pm MDT, 8:23 pm PDT) and the whole show should be over (meaning no obvious darkening of the Moon visible by ~5:20 UT.

Here in Tucson, the Moon will appear to rise at due east and will be observable in the southeastern sky for the entire eclipse.


View of the eastern horizon at the time of mid-eclipse for Tucson, Arizona. Chart created with Stellarium.

If you have a pair of binoculars or are taking images of the eclipse, note that two other relatively bright solar system objects are near the Moon. The planet Uranus is located ~15° to the due east or lower left of the Moon. At that time Uranus will be magnitude 5.7 (barely visible to naked eye observers from dark sites) and located 19.98 AU from the Sun and 19.02 AU from Earth (that’s 1.86 million miles from the Sun and 1.77 million miles from Earth). The Moon will be 0.0024 AU from the Earth (222,000 miles from the center of the Earth) or ~7900 times closer than Uranus. To the southeast of the Moon and about 11° away is the brightest asteroid, (4) Vesta. It will be 2.42 AU (225 million miles) from the Sun and 1.43 AU (133 million miles) from Earth or ~600 times further away than the Moon. Vesta will be a little fainter than Uranus at magnitude 6.2. Use the star chart below to find Uranus and Vesta.


Location of Uranus and asteroid Vesta relative to the eclipse Moon on Sunday evening Sep. 27. Chart created with Stellarium.

The next lunar eclipse will be on 2016 March 23 but will be a rather poor penumbral eclipse (meaning the darkest part of the shadow doesn’t cross the Moon). The next series of total lunar eclipses occur on 2018 January 31, 2018 July 27, and 2019 January 19. The first and third of this triad are visible in the US. Go to the NASA Lunar Eclipse page for more detail on these and other lunar eclipse.