As India is getting ready for a special Solar Eclipse on June 21st, astronomy enthusiasts have another celestial event to cherish to. On the night between June 05-06 the Moon will pass through the penumbral shadow of Earth causing a “Penumbral Eclipse of Moon”.
So what is a Lunar Eclipse? A lunar eclipse is a special celestial alignment where the Moon moves inside the shadow of Earth while orbiting around it. The lunar eclipses always happen on the full Moon night when the Moon is positioned on one side of Earth while the Sun is on the other side. As the Moon moves through the umbral shadow completely, it causes total lunar eclipse however if part of the Moon moves through the umbral shadow only, it is called partial lunar eclipse. When the Moon is inside the penumbral shadow only, penumbral lunar eclipse happen but this time, even half of the Moon will be outside of the penumbral shadow of the Earth. It means the Moon will only experience partial change in brightness on the surface which will not be very significant.
So what is Umbral and Penumbral shadow?
Every object when exposed to light cast two different kind of shadows. The darker and central part of the shadow is called Umbra or umbral shadow while the fainter outer limb of the shadow is called Penumbra or penumbral shadow.
The eclipse will start at 11:15 pm on the night of June 05 and will continue till the early morning hours of June 06 at 2:34 AM. The eclipse will have an umbral magnitude of -0.4053 where as the penumbral magnitude of 0.5683. The numbers means that 56.83% of Moon will be in the penumbral shadow of Earth while it will miss the umbral shadow by 40.53%. The Moon will be full at 00:42 am on June 6 and the maximum eclipse will be at 00:55 am. The Moon will be at 38.5 degrees about the ground while face south – south west when at maximum. This full Moon is called Strawberry Moon in Old Farmer’s Almanac.
The eclipse will be partial penumbral lunar eclipse which means it will partially submerged in the penumbral shadow of the Earth. Here is a video of what the eclipse will look like through a telescope over a period of time. Also in this video, you will notice what one could see if they were living on Moon and towards the Southern Hemisphere.
So how frequent these eclipses are?
The eclipses occur almost every 6 months. The reason for its periodic occurrence is the inclination between the orbital plane of the Earth around Sun and the Moon around the Earth. This inclination is about 5 degrees. So in every orbit around the Earth, the Moon moves about 5 degrees up or down with respect to the orbital plane of Earth around Sun. The point where the two planes intersect, it is called node. there are 4 nodes every year. When the Moon is at one node and near its full phase or new phase, there will be an eclipse.
The duration of Moon travel between first two nodes say N1 and N2 is about 15 days and between N2 and N3 is about 180 days and then about N3 and N4 is about 15 days and then again N4 and N1 will be about 180 days. The path of Moon may cause a series of eclipses within a span of 30 days which is either Lunar – Solar – Lunar eclipse or Solar – Lunar – Solar eclipse. It depends on which eclipse happen on the time of N1 or near to it. Although three eclipses back to back are rare, a pair of Solar and Lunar eclipses is very common.
In the current series 3 back to back eclipses will take place namely Lunar – Solar – Lunar eclipse. First of the three eclipses will be visible on June 05, 2020 from India, while the next in the series a solar eclipse which would be annular, will also be visible from India (read here) on June 21. The last of the three, another partial penumbral lunar eclipse will not be visible from India but will occur on July 6, 2020 (IST)
This year there are four lunar eclipses and two solar eclipses happening. First Lunar eclipse occurred on Jan 10-11 2020 while the next will happen on June 05-06. First solar eclipse will happen on June 21st.
Astrophile Education Services will conduct a live webcast of the upcoming Partial Lunar Eclipse of June 05-06, 2020 and you are advised to subscribe to our channel for more such events and sessions broadcasted live. The link to the youtube live broadcast is: