Saturday: Venus
will really be negative for the next few nights. But, don’t feel bad for Venus.
It is okay for a celestial object to be negative as long as we are referring
only to its magnitude. The ancient Greek astronomer Hipparchus developed a
system for rating the apparent brightness of stars and planets in which lower
numbers refer to brighter stars and planets. In his initial scheme, all points
of light in the night sky were classified from first magnitude, meaning bright,
to sixth magnitude, meaning very dim. Modern day astronomers have made this
scale more quantitative. Tonight and tomorrow, Venus has a magnitude, or
apparent brightness rating, of -4.5. Sirius, the brightest star in the night
sky, has a brightness rating of -1.5. That’s about the same magnitude as
Jupiter is tonight. Venus is about a half a fist held upright and at arm’s
length above the west-northwest horizon at 10 p.m. Jupiter is about a half a
fist to the right of Venus. The star Regulus is less than a half fist to the
upper left.
Sunday: 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 west horizon at 11:00 p.m.
Monday: Saturn
is two and a half fists above the south horizon at 10 p.m.
Tuesday: New
Horizons arrives at Pluto at about 4:50 a.m. PDT. But don’t be waiting by your
computer for the latest images. First of all, it takes about five hours for the
signal to get from Pluto to Earth. Second of all, New Horizons will be spending
hours with its instruments pointed toward Pluto, not Earth. NASA TV will host a
show from mission headquarters from about 5:30-6:15 p.m. PDT today to broadcast
the celebration when the first signal from Pluto arrives. From 1:00 to 2:00
p.m. tomorrow, NASA TV will show the first close-up images from Pluto. For more
information about NASA TV coverage of the event, go to https://goo.gl/oCtlGd. For more information
about the mission, go to http://pluto.jhuapl.edu/.
Wednesday:
Mercury is less than a half a fist above the northeast horizon at 5 a.m. If you
have binoculars, you may be able to spot a much dimmer Mars to the lower left
of Mercury.
Thursday: The
long summer days remind us to take some time to safely observe the Sun. The
best way to do that is to go to http://sdo.gsfc.nasa.gov/ and watch
the great images and videos that come from the Solar Dynamics Observer, or SDO
for short. We are just moving away from a sunspot maximum so the Sun has been
very active lately. So what, you say? Sunspots and associated phenomena greatly
influence the strength of solar flares. The strongest flares can affect
satellites orbiting the Earth and even electronics on the Earth’s surface.
Friday: Say
"Cheese". 165 years ago today, Vega, in the constellation Lyra the
lyre, became the first star ever photographed. The photograph was done at the
Harvard Observatory using the daguerreotype process. Vega is the third
brightest nighttime star we can see in Ellensburg, behind Sirius and Arcturus.
Vega is nearly straight overhead at 11:00 tonight.
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 http://nightsky.jpl.nasa.gov/planner.cfm.
No comments:
Post a Comment