Saturday: Let’s learn about Capella. It is the fourth brightest star we can see in Ellensburg. It is the most northerly bright star. It is a binary star consisting of two yellow giant stars that orbit each other every 100 days. At 10:17 p.m., Capella is less than a half a fist held upright and at arm’s length above due north. You can also use the Big Dipper to find it. First, find the two “cap” stars on the cup of the Big Dipper, the stars on the top of the cup. Draw a line from the “cap” star closest to the handle to the cap star farthest from the handle. Then, continue that line to the next very bright star, which is Capella. Thus, you can “cap” to Capella. If you can’t “cap” tonight, don’t worry. Capella is the brightest circumpolar star meaning it is the brightest star that never goes below the horizon from our point of view in Ellensburg.
Sunday: Zubenelgenubi, the second brightest star in the
constellation Libra. The name means "southern claw", a holdover from
the time when this part of the sky was associated with the neighboring
constellation of Scorpius the scorpion. Zubenelgenubi is a binary star system,
easily seen with binoculars as a white and yellow pair. To a person living on a
planet orbiting the dimmer of the two stars, the brighter star would be nearly
as bright as the full Moon appears from Earth. Zubenelgenubi is one and a half
fists above due southwest at 10:30 p.m.
Monday: The bright star Spica is about a finger width to the
lower left of the moon at 10:00 p.m. They are low in the southwestern sky.
Tuesday: The Gemini twins, first Castor and then Pollux,
rise just before the Sun. They are both less than a fist above the northeastern
horizon at 4:45 a.m. Pollux is the brightest star, as measured from Earth, with
a confirmed planet in orbit. It is likely that there are brighter stars with
undiscovered planets.
Wednesday: What you see with the naked eye isn’t all that
can be seen. While astronomers can learn a lot from observing the sky in the
visible wavelengths, many celestial objects radiate more light, and more
information, in wavelengths such as radio, microwave, infrared, ultraviolet,
x-ray, and gamma ray. In 2012, NASA launched the Wide-field Infrared Survey
Explorer (WISE) to study objects that radiate in the infrared range such as
asteroids, cool dim stars, and luminous galaxies. For an interesting comparison
of how different wavelengths show different aspects of celestial objects, go to
http://goo.gl/nvuax. If it weren’t for
infrared telescopes such as WISE, astronomers would not know about the
significant amount of dust in galaxies. We also wouldn’t know how much
brighter than the Sun red supergiant stars are. Antares is a red supergiant
star, currently sitting at one and a half fists above the southern horizon. In
the visible wavelengths, Antares shines 10,000 times brighter than the Sun. But
since Antares is much cooler than the Sun, its energy distribution peaks in the
infrared. So across all wavelengths of light, Antares shines 60,000 times
brighter than the Sun. The new James Webb Space telescope is also an infrared
telescope.
Thursday: Saturn is one fist above the east-southeastern
horizon at 11:00 p.m. Jupiter is about a half a fist above the
east-northeastern horizon at 1:00 a.m.
Friday: Antares is about a half a fist to the right of the
moon at 10:00 pm. They are low in the southern sky.
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.
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