Saturday: Happy Asteroid Day (http://www.asteroidday.org/),
the day we celebrate avoiding the destruction of the Earth by an undiscovered
asteroid. There are 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.
Sunday:
Celebrate Asteroid Day with Vesta, the brightest asteroid as seen from Earth. First,
find Saturn, about two fists above the south-southeast horizon. Get Saturn on
the left hand side of your binocular field of view. There should be a large,
fuzzy object on the right half of your field of view. That’s the Lagoon Nebula.
(More about that next week.) Move the Lagoon Nebula to the lower left part of
your field of view. Then, move your binoculars up and to the right. You will
come to a triangle with three stars at its base and one point of light at its
peak. This point of light is Vesta. Follow what you think is Vesta over the
next few nights. If it moves slightly from night to night, it is Vesta.
Monday: This
is a good time of the year to find the Big Dipper. The handle is nearly
straight overhead at sunset. The cup is in the northwest sky. You can always
use the Big Dipper to find some other bright stars. First, follow the curve, or
arc, of the Big Dipper down three fists into the southern sky. This is the
bright star, Arcturus, the second brightest nighttime star we can see in
Ellensburg. Next, continue on a straight line, or spike, another three fists
down toward the south horizon to the star Spica. Spica is the tenth brightest
nighttime star we can see in Ellensburg. It is known as the Horn Mansion, one of
28 mansions, or constellations, in the Chinese sky. You now know how to use the
Big Dipper handle to “arc” to Arcturus and “spike” to Spica.
Tuesday: At
9:30 p.m., Mercury is nearly one fist above the west-northwest horizon, Venus
is one and a half fists above the west horizon, Jupiter is two and a half fists
above the south horizon, and Saturn is one fist above the southeast horizon.
What about Mars, you say? Wait a couple of hours. Then Mars is a half a fist
above the southeast horizon.
Wednesday: When it is sitting low in the western sky, many people mistake
the star Capella for a planet. It is bright. It has a slight yellow color. But,
Capella is compelling on its own, even though it is “just” a star. 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 p.m., Capella is a half a fist above the
north-northwest horizon. 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 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’ it 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.
Thursday: This Saturday, the CWU Physics Department and the College of the
Sciences is hosting its First Saturday planetarium show from noon to 1 pm. CWU
physics professor Tony Smith will give a show called Space: The Fun and the
Fiction. Hurry up and make the Kessel Run in twelve parsecs so you can come to
the presentation. There will be a show at noon on the first Saturday of every
month hosted by different CWU astronomers and astronomy educators. These shows
are free and open to all ages. The planetarium is room 101 in Science Phase II,
just off the corner of 11th and Wildcat Way, H-11 on the campus map found at https://www.cwu.edu/facility/campus-map.
Friday: Hot
enough for you? Don’t blame the Earth-Sun distance. Surprisingly, the overall
temperature of the Earth is slightly higher in July, when the Earth is farthest
from the Sun, than in January, when it is closest. That’s because in July, the
Northern Hemisphere is tilted towards the Sun. (This is the real cause of the
seasons.) The Northern Hemisphere has more land than the Southern Hemisphere.
Thus, in July, the large amount of Northern Hemisphere land heats up the entire
Earth about two degrees Celsius warmer than in January. In January, the watery
Southern Hemisphere is tilted toward the Sun. But, water does not heat up as
fast as land so the Earth is a few degrees cooler. The distance between the
Earth and Sun is its greatest today, 152.1 million kilometers. This is called
aphelion from the Greek prefix “apo” meaning “apart” and Helios, the Greek god
of the Sun.
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.