Saturday: Tonight
is a great night to look for the Big Dipper. Tomorrow will be a great night to
look for the Big Dipper. In fact, every night for many centuries will be great
nights to look for the Big Dipper. But the Big Dipper’s shape slowly changes
over many, many, many, many centuries. (Have I reached my word count yet?) Tens
of thousands of years ago, it didn’t look like a dipper and tens of thousands
of years from now, it will no longer look like a dipper. For a short video
simulation of the changing Big Dipper, go to http://goo.gl/df1yV. For a
look at the current Dipper, face northeast at 8 p.m. The lowest star, Alkaid,
is two and a half fists above the horizon.
Sunday:
If you ask an astrobiologist for the three most likely places to find evidence
of life in the Solar System, other than Earth, they’d probably say Mars, Europa
(“Didn’t they sing “The Final Countdown”?”), and Enceladus. Mars makes sense
because you know scientists have sent a lot of probes there. Astronomers first
discovered strong evidence of a large water ocean on Europa, a moon of Jupiter,
in 1989. However, Enceladus, one of Saturn’s moons, first piqued
astrobiologists’ interest a few years ago then NASA’s Cassini probe discovered
jets of water containing organic materials shooting out. Two years ago, the
German space agency started a project called Enceladus Explorer, EnEx for
short, to collect sample from deep within Enceladus. For more information on the
Enceladus mission, go to http://goo.gl/VPxzs.
At 6 a.m., Mars is two fists above the south horizon and one and a half fists
to the left of the Moon. Jupiter and Europa are about one fist above the west
horizon. Saturn and Enceladus are two fists above the south horizon and two
fists to the left of Mars. By the way, the Swedish group Europe sang
“The Final Countdown”. And they were “heading for Venus” in the song, not to
the worlds of the outer Solar System. Venus is just above the east-southeast
horizon.
Monday: It
is often said that Earth is a water world because about 70% of the Earth’s
surface is covered by water. What would it look like if all that water on the
surface were gathered up into a ball? That “ball” would be about 700 km in
diameter, less than half the diameter of the Moon. The Astronomy Picture of the
day shows us right here http://goo.gl/4wXLM.
Tuesday: In
this busy world, it is important to know what time it is. We have many devises
that give us the time. A phone. A computer. A watch. But who has time to build
a phone, computer or even a watch. Not you. But everyone has enough time to
build a simple Sun Clock. All you need is a pencil, a compass and a print out
of the clock template. Go to https://www.exploratorium.edu/science_explorer/sunclock.html for more
information.
Wednesday:
Jupiter is one fist above due east at 7 p.m.
Thursday:
Avast ye matey. Swab the poop deck. Pirates love astronomy. In fact, the term
“poop” in poop deck comes from the French word for stern (poupe) which comes
for the Latin word Puppis. Puppis is a constellation that represents the raised
stern deck of Argo Navis, the ship used by Jason and the Argonauts in Greek
mythology. Argo Nevis was an ancient constellation that is now divided between
the constellations Puppis, Vela and Carina. The top of Puppis is about a fist
and a half to the left of the bright star Sirius low in the southern sky at 9
p.m. Zeta Puppis, the hottest, and thus the bluest, naked eye star in the sky
at 40,000 degrees Celsius is near the uppermost point in Puppis.
Friday: Astronomers
estimate that asteroid 2013 TX68 will pass “close to” Earth. How close? It
could be as close as 11,000 miles – just about one Earth-diameter away. It
could be 9 million miles – about one fifth the distance to Mars. The
uncertainty is so large because we don’t know enough about its orbit.
Thankfully, this close encounter will help astronomers pin it down so we know
the chances of being struck by 2013 TX68 in the future. For more information
about 2013 TX68 and other near Earth asteroids, go to http://goo.gl/6kf8bo.
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.