Another eclipse coming in February

Well, you pays your money and you takes you chance. That is the way it was with the lunar eclipse on Aug. 28, at least in this area. The bane of all astronomers -- the clouds that sometimes block any chance of viewing heavenly events were in great abundance. Such it was for the eclipse. I know the red of the eclipse was dazzling from descriptions of other astronomers who were able to watch it.

I guess we will have to wait until Feb. 20 of next year when there will be another total lunar eclipse. That eclipse will start just after the Moon rises and will be over by midnight. No late hours for this one. The only down side is it won't be warm in February.

One major summer constellation we haven't looked at before is Hercules. Named for the famous strong man of Greek mythology. Hercules can be found almost directly overhead on these early warm summer evenings. A little to the west side of the sky later on into the night.

The best way to describe the constellation is a giant letter "H" laying on its side. To find it look for Cygnus the Swan (or the Northern Cross). One of the constellations of the Summer Triangle. Find Deneb, the tail star, and draw a line from it to Virgo, the brightest star in Lyra. Vega is also one of the stars of the Summer Triangle.

Follow that line to the west to find Hercules which consists of several second and third magnitude stars. One identifying mark of Hercules is an asterism called the "Keystone." The Keystone is a trapezoid shape in the middle of the "H."

The only truly outstanding feature of Hercules is one found by French comet hunter Charles Messier which he placed at number 13 on his list of things that were not comets.

M13 is, in fact, a dazzling example of a globular star cluster. It is considered the finest in the northern hemisphere. From very dark country skies it is visible to the eye alone along the bottom side of the Keystone (if you are looking west) about one-third of the way down from right to left.

In binoculars, it takes on an indistinct fuzzy blob shape but through a telescope it begins to reveal the wonders it holds. A million stars compacted into an area of space about 160 light years across. A light year is the distance light will travel in one year, or about six trillion miles.

I have often wondered what the sky would look like to anyone living on a planet circling a star in a star cluster. From our view point M13 is a mass of stars all packed together with some stragglers on the outside edge. But what would it look like from the inside? How would the sky appear? Would it be the mass of stars we see from Earth or would it look like our sky only a little more crowded?

For an answer to those questions I went to Robert Burnham, Jr.'s classic "Celestial Handbook." In discussing this very thing he says, "The central region covers an area some 100 light years across, or roughly a million cubic light years in volume. Assuming that a million stars populate this region it is evident that the density is no greater than about one star per cubic light year. In the actual center of the cluster the star density may be several times greater. But in no case would it approach actual crowding."

Keep in mind that the nearest star to Earth, other than the Sun, is Proxima Centauri which is 4.2 light years away.

Well, so much for a massive, star-crowded, night sky.

SKY WATCH:

New Moon on Sept. 11. Since we had a total lunar eclipse last month this New Moon will bring a total solar eclipse, but it will be visible only to those living in Argentina and Antarctica. Just keep in mind, our turn here in southwest Nebraska is coming in 2017 when we will have a ring side seat for a total solar eclipse. Jupiter is still holding forth in the south in the early evenings with his fellow-travelers in Scorpius. Mars pops over the eastern horizon at about midnight and Venus joins the morning crew at about 5:30 a.m.

Next time:

More astronomical blatherings.