Saturday: Nearly 400 years ago, Galileo looked at the Pleiades star cluster through his telescope and noticed that the seven or so stars in the region visible to the naked eye became many more. There are two main types of star clusters. Open star clusters, like the Pleiades and the Beehive, are groups of a few dozen to a few thousand stars that formed from the same cloud of gas and dust within our galaxy. Stars in open star clusters are young as far as stars go. Globular clusters are groups of up to a few million stars that orbit the core of spiral galaxies such as our own Milky Way. One of the most well-known star clusters is the globular cluster in Hercules, an object that is fairly easy to find with binoculars. First find Vega, the bright bluish star six and a half fists held upright and at arm’s length above the eastern horizon at 11:00 p.m. Two fists above Vega, and close to straight overhead, is a keystone shape that represents the body of Hercules. Aim your binoculars at the upper left-hand star of the keystone, the star closest to straight overhead. The globular cluster is one third of the way to the rightmost star of the keystone. It looks like a fuzzy patch on the obtuse angle of a small obtuse triangle. If you don’t know what an obtuse angle is, you should not have told your teacher, “I’ll never need to know this math stuff you are teaching”.
Sunday: Jupiter is about a half a fist above the
west-northwestern horizon at 9:45 p.m. Mercury is below it, likely too close to
the horizon to be visible. They are moving towards the Sun in the sky and will
soon be lost in its glare. At one and a half fists above the western horizon,
Venus is still far enough from the Sun in the sky to be visible in the evening
sky for a few more weeks.
Monday: The July full moon is the Buck Moon, named for the
new antlers that form on the forehead of male deer this time of year.
Tuesday: Happy Asteroid Day (http://www.asteroidday.org/), the day we
celebrate avoiding the destruction of the Earth by an undiscovered asteroid.
There are about a million asteroids in the Solar System with the potential to
strike Earth and destroy a city. Astronomers have discovered only 1% of them.
Asteroid Day is an effort to educate the public and encourage policy makers to
fund this important effort. King Tut may have celebrated an ancient Asteroid
Day by asking his assistants to make a dagger out of a broken-off asteroid that
landed on Earth. Astronomers discovered that the blade of the knife contained
much more nickel than is found in terrestrial iron, an amount consistent with
iron meteorites, especially with one found in the year 2000 in the Kharga
region in northern Egypt. For more information about the dagger, go to http://goo.gl/BHBivd.
Wednesday: Mizar is a star in the middle of the Big Dipper
handle. Don’t confuse Mizar with its rhyming brother Izar in the constellation Boötes.
Izar is also a binary star with about the same apparent brightness. And both
were featured in different episodes of Star Trek. Izar was featured in the Star
Trek episode “Whom Gods Destroy” from the original series. It is the base of
Fleet Captain Garth, a former big shot in the federation and one of Kirk’s
heroes before he went insane. Garth kidnaps Kirk and Spock before eventually
being outsmarted. Mizar doesn’t play as big a role in its episode. It is the
star of the home world of one of the alien species in The Next Generation
episode “Allegiance”. Izar is one fist above the bright star Arcturus and
exactly six fists above the west-southwestern horizon at 11:00 p.m. Mizar is
nearly six fists above the west-northwestern horizon.
Thursday: Being in a coma is a bad thing. Looking at the
Coma Star Cluster is a good thing. The Coma Star Cluster is an open cluster of
about 50 stars that takes up more space in the sky than 10 full Moons. It looks
like a fuzzy patch with the naked eye. Binoculars reveal dozens of sparkling
stars. A telescope actually diminishes from the spectacle because the cluster
is so big and the telescope’s field of view is so small. The Coma Star Cluster
is in the faint constellation Coma Berenices (ba-ron-ice’-ez) or Queen
Berenice’s hair. Queen Berenice of Egypt cut off her beautiful hair as a
sacrifice to the gods for the safe return of her husband Ptolemy III from
battle. The Coma Star Cluster is about three fists above the western horizon at
11:00 p.m.
Friday: Mars is about one and a half fists above the
east-northeastern horizon at 4:30 a.m., halfway between the Pleiades and Hyades
open star clusters. But that’s not the most interesting thing about looking at
Mars this morning. The planet Uranus is right above Mars in the sky this
morning. Uranus is not quite bright enough to be visible to the naked eye. But
it is easily visible with binoculars, right above Mars.
The positional information in this column about stars and
planets is typically accurate for the entire week. For up-to-date information
about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
All times are Pacific Time unless noted.
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