Saturday February 11th the full Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic, so there are two node intersections, the ascending and descending nodes.
When a node crossing happens near the time of a full or new Moon there is a chance for an eclipse. The closer the two times are to each other the more centered the Moon will be with respect to the Sun for a total eclipse, or more centered such that the Moon passes through the inner and darker umbral shadow.
That is the situation for this weekend with full Moon at 0:33 UT Saturday January 11th (6:30 pm CST Friday January 10th), and the node crossing at 19:50 UT (1:50 pm CST) Saturday. This time, due to the nearly 20 hour difference the Moon’s orbital path will take it across the Earth’s fainter outer, the penumbra. A penumbral lunar eclipse is not that easily noticeable because the bright reflected light from the Moon is not dimmed that much as the Moon passes through the penumbra.
Click here to go to the Hermit Eclipse web site for more information about this eclipse.
Adding to the viewing there is a good chance Comet 45P/Honda-Mrkos-Pajdusakova, aka the “Green Comet”, will be bright enough to be seen with binoculars over the next several evenings. On the 11th the comet will be at its closest to the Earth and may be brighter than 4th magnitude. Unfortunately the Moon’s reflected light will brighten the sky making it that much more challenging to see the comet. Click here to read an article about the comet at the EarthSky web site.
Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*
*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)
Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”
Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.