Monday morning, 28 April, at 6:37 am CDT (11:37 UT) the waning but nearly new Moon will be crossing the plane of the ecliptic moving south. This is known as the descending node, one of two intersections the Moon’s orbital path has with the plane of the ecliptic. The plane of the ecliptic, or just ‘the ecliptic’ in reality is the Earth’s orbital path around the Sun.
Coincidentally the time for new Moon is 1:17 am CDT (6:17 UT) 29 April, and when the time for these two events, node crossing and new Moon or full Moon, is this close we have a solar eclipse. This time around we have an annular eclipse that unfortunately is best viewed (if possible) from a rather remote area of the world – Antarctica.
An annular solar eclipse at new Moon phase occurs with the same arrangement for a total solar eclipse at new Moon phase with the difference being that with an annular eclipse the Moon is further from the Earth. This results in the Moon having a smaller apparent diameter then the Sun, and so at mid-eclipse the disk of the Moon does not completely cover the sun’s disk. This leaves a ‘ring of fire’, the annulus, around the Moon.
How does the Moon get further from the Sun is explained by knowing the Moon’s orbital path is elliptical rather than circular so its distance from the Earth at various phases varies. See a recent post about the Moon at perigee for more about this.
Click here to see eclipse information from NASA. (PDF)
Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.