|What's Up...Night sky tongue twisters|
Okay, you caught me. For all those sharp-eyed readers who caught it last week when I called the Lagoon Nebula M7 when, in fact, it should be called M8. All I can say in my defense is fat fingers, small keys, and bifocals. But, thanks for noticing.
M7 is a small, rather delightful open star cluster just below and right of the M8/M20 pair. Locate Shaula, the “stinger” stars of Scorpius, and go left about five degrees (about the width of your fist held at arm’s length).
If you put Shaula on the right side of your binocular field of view, M7 will be on the extreme left edge. M7 is also known as Ptolemy’s Cluster after early astronomer Claudius Ptolemy, a Roman citizen living in Egypt in the first century. He recorded his observation of the cluster in about 130AD.
The M7 cluster contains about 80 stars and is estimated to be between 800 to 1,000 light years away. Some other open star clusters are the Pleiades and the Hyades clusters. Both are located in the area of the constellation Taurus, the Bull.
M7 can be seen without any optical aid from a dark-sky location and binoculars increase the number of stars you can see, but a telescope will give a much better view.
While you are in the area of M7, put it at the eight o’clock position in your binocular field of view. At the two o’clock position will be another very nice open cluster, M6, the Butterfly Cluster, so named for its shape.
See, I told you there are lots of things to find in the area around Sagittarius and Scorpius so just keep looking.
Okay, now, where was I? Oh yes, the tongue twister. Alright, lets go back to Scorpius which is located almost due south about an hour after sunset. Find Antares, the bright, reddish star at its heart.
Up and right of Antares are the three stars marking the beast’s head. Draw a line from Antares going about halfway between the middle and left stars of the head on out to a bright, third magnitude star in Libra, the Scales.
This is the first of our two tongue twister stars, Zubeneschamali (ZUBEN-es-shamali) which is Arabic for Northern Claw.
Years ago this star, and our other tongue twister Zubenelgenubi, marked the extended claws of the scorpion. However astrologers (note please, astrologers, not astronomers) wanting to complete the 12 constellations of the Zodiac needed one more between Scorpius and Virgo so they borrowed the two claw stars and turned them into Libra, the Scales.
Zubenelgenubi (ZUBEN-el-jenubi) is Arabic for southern claw. It is a blue star shining at about third magnitude and can be found by starting at Antares and drawing a line passing almost halfway between the middle and right star of the head of Scorpius. It is located about 160 light years away and is about 130 times brighter than our Sun and shines as bright as 44 Suns.
SKY WATCH: First quarter Moon, July 18. Tonight a four-day old Moon is located just below and left of bright Venus. Look about a half-hour after sunset in the west.
Another planet has joined the parade of planets in the western sky. Mercury is just above the horizon very near our old friend M44, the Beehive Cluster. It is very close to the horizon. You may want to wait until later in the month when the speedy planet will be in conjunction with Regulus in Leo.
Tomorrow night, July 15, the Moon will be about five degrees below Mars and 10 degrees below and right of Saturn. After midnight Jupiter and Uranus join the crowd rising in the east. Both can still be seen in the same binocular field of view. There is one star between the planetary pair a little dimmer than the blue-green planet.
Just a note, they can be viewed from town but a dark-sky place is better.
NEXT TIME: More astronomical blathering.