Saturday: Two of the best, and certainly the most available, tools for viewing the night sky are your eyes. Your eyes let you see the entire sky in just a few seconds. Your eyes can read star charts, decipher astronomy apps, and spot meteors while your friend is still setting up her tripod. Your naked eyes are not as effective as gathering light. They work well when the light source is comparatively bright and the detailed features are fairly large. It’s best to practice on a special Solar System body known scientifically as the Magnificent Optical Object of Nearness. Artists such as Jan van Eyck and Leonardo da Vinci produced the first realistic naked eye depictions of the Magnificent Optical Object of Nearness. I challenge you to use your unaided eyes to observe craters on the Magnificent Optical Object of Nearness, better known as the Moon. For a guide to the most prominent craters, go to http://goo.gl/JLhraO.
Tonight’s and tomorrow night’s moon is the second full moon
of the month, which is called a blue moon. That name originates from a
mistranslation of a story from the 1500s.
Sunday: You know Metis and Thebe and Adrastea and Amalthea.
Io and Ganymede and Callisto and Europa. But do you recall? There are 97 Jovian
moons in all. Just 60 years ago, Jupiter was thought to have only 12 moons. But
astronomers are red nosed with delight that the advent of supersensitive
electronic cameras has caused the number of discovered moons to rapidly
increase. Jupiter’s 115 moons range in size from Ganymede, the largest in the
Solar System with a diameter of 5,262 kilometers, to numerous moons with
diameters of only one kilometer. In the past few years, Saturn moved to first
place in the moon race with 292 moons. Uranus follows Jupiter with 29. Then
comes Neptune with 16, Mars with 2, and Earth with 1. Our moon is the fifth
largest in the Solar System, with a diameter of 3,475 kilometers. (One
kilometer is 0.62 miles.) Even dwarf planets have moons. Pluto has 5 while both
Haumea and Quaoar have 2. Eris, Makemake, Orcus, and Gonggong have 1 each. Eris
is an outer solar system object that was discovered in 2005 and named in
September of 2006. Because astronomers thought it was larger than Pluto, people
called it the tenth planet for a while. (More recent measurements show Eris to
be a little smaller in diameter than Pluto.) Haumea, the newest dwarf planet
with a moon, was discovered in 2004 and officially named a dwarf planet on
September 17, 2008. Go to https://solarsystem.nasa.gov/moons/
for more information about Solar System moons. You’ll have to wait until
tonight to see our moon and to see some of the other Solar System planets that
have moons.
Monday: Jupiter, Venus, and Mercury and all low in the
west-northwestern horizon at 9:45 p.m. Jupiter is nearly two fists above the
horizon, to the upper left. Venus, the brightest of the three, is in the
middle. Mercury, on the lower right, is about half a fist above the horizon.
Tuesday: Summer is nearly here. How do I know? Because the
days are very long. Because the temperature is rising. Because the school year
is ending. Also, because the Summer Triangle is fairly high in the eastern sky
at 11:30 p.m. Vega, the third brightest star visible from Ellensburg, is about
five fists above the eastern horizon. Deneb, at the tail of Cygnus the swan, is
about three and a half fists above the east-northeast horizon. The third star
in the triangle, Altair in Aquila the eagle, is nearly two fists above the
eastern horizon.
If you want to put somebody off, tell them to wait until
Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star
meaning it never goes below the horizon.
Wednesday: At 4:15 a.m., Mars is half a fist above the
east-northeastern horizon and Saturn is one and a half fists above the
east-southeastern horizon.
Thursday: Antares is one and a half fists above the
south-southeastern horizon at 11:45 p.m.
Friday: The bright star Capella is a half a fist above the
north-northwestern horizon at 11:30 p.m. Interestingly enough, even though it
is in the northern sky, it is only about two fists from the Sun. If you viewed
Capella from Ketchikan, the southernmost city in Alaska, Capella would be one
and a half fists above the horizon. The Sun would be a half a fist below the
horizon, close enough to the horizon that there would be a constant twilight
glow.
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.