Friday, September 11, 2015

An Alignment of the Four Most Important Objects in the Solar System

Sunday morning, September 13, 2015, we will have an alignment of the four most important objects in the solar system. SDO, the Earth, the Moon, and the Sun will form a line in space. From 0614 UTC (2:14 a.m. ET), when the Earth's edge touches the edge of the Sun, until 0721 UTC (3:21 a.m. ET), when the Moon's edge leaves the Sun, SDO's field of view will be blocked by either the Earth or Moon. The attached movie was produced by the SDO flight operations team to show how the eclipse and lunar transit will look from SDO. This is the first time an eclipse by the Earth and a lunar transit will be seen by SDO. (Although we can see features on the Earth and Moon in the video, we cannot see them in the SDO cameras.)

But that's not all! At 0655 UTC (2:55 a.m. ET) a partial solar eclipse will be visible in Antarctica. The path of the solar eclipse starts in southwestern Africa and goes almost over the South Pole. On the left is a picture from NASA's Eclipse webpage showing the path of the solar eclipse. This is the first time a solar eclipse was visible on the Earth during an SDO lunar transit. SDO cannot see the entire solar eclipse because the Earth gets in the way. The Moon was at perigee (closest point to the Earth) for the Full Moon two weeks ago. That means it is at apogee (furthest point from the Earth) for the New Moon on Sunday. The Moon will appear to be a little smaller than average so a total solar eclipse is not possible this month.

On September 28, 2015 a total lunar eclipse will be visible from most of the United States, Europe, South America and Africa. SDO does not see lunar eclipses because we look the other way. Not to worry, SDO will see another Lunar Transit on October 12, 2015 from 1718 – 1733 UTC (1:18 – 1:33 p.m. ET). It will be a grazing transit. Because SDO will not be near midnight Mountain Time, this transit will not be seen at the surface.

I hope you enjoy the Alignment of the Four Most Important Objects in the Solar System.