Download August - Joliet Junior College

AUGUST 2012 ASTRONOMY
From the Trackman Planetarium at Joliet Junior College
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At 31 minutes past midnight (CDT) on August 6th, the new Mars Rover named
Curiosity will land on the surface of Mars. The Rover is 10 feet long, 7 feet high and 9
feet wide and weights about 2,000 pounds on Earth. During its 7 minute descent
through the Martian atmosphere it will use a parachute, rockets, and a sky crane to land
it safely on the surface. Once on the surface of Mars, the Rover will search areas of
Mars for past or present conditions favorable for life. Mars will be 154.3 million miles
from Earth when the Rover lands. Radio signals from the rover will take 14 minutes to
reach Earth meaning the first signals from the entrance into the Martian atmosphere
won‘t reach Earth until seven minutes after the rover has landed.
Saturn and Mars are in the western sky after sunset. Mars is moving towards Saturn
and on August 17th Saturn will be 3 degrees from the red planet. Saturn and Mars are
the only planets visible in the evening sky during August. Jupiter and Venus are in the
sky before sunrise. Venus is very bright and easily found. Jupiter is the bright object
above Venus. Venus will be at its farthest west on August 15th and will start to orbit
back toward the sun after the 15th. Venus will pass behind the sun next March. Jupiter
will appear to be moving away from Venus and Jupiter will be rising in the late evening
sky in September. Mercury is in the morning sky before sunrise, and on August16th
Mercury will be at its greatest distance from the sun before orbiting back toward it.
Mercury will be rising 90 minutes before the sun on the 16th and it will be a good
opportunity to find the evasive planet in binoculars or a telescope.
The Milky Way crosses the high in the evening sky during August, but you need to be
in dark skies to find it with the naked eye. There are three bright stars above us in midevening that form the summer triangle. If you look between the stars of the triangle
with binoculars, you should see many of the stars that make up our galaxy. Look low
in the southern sky at mid-evening and you will see a group of stars that form a teapot!
That is Sagittarius (The Archer) but it looks more like a teapot than the man/horse it is
suppose to represent. The center of our galaxy and the black hole at the galaxy’s center
are at the end of the teapot’s spout. Up and to the right of Sagittarius is Scorpius - the
Scorpion. The scorpion with its claws is easy to find. The red star in the scorpion’s tail
is Antares. Antares is 2,700 times larger than our sun. And for the fans of Pluto - Pluto
is right above the lid of the teapot. High in the northeast is the “W” that forms the
constellation of Cassiopeia.
A new moon was discovered orbiting Pluto. We now know the dwarf planet has at
least five moons. We will know a lot more when the space probe New Horizons arrives
at Pluto after a nine and one half year journey in July, 2015.
The Perseids Meteor Shower is on the evening of August 12th. (And one or two
evenings before and after the 12th.) The Perseids is one of the best meteor showers of
the year with about 80 meteors per hour at its maximum. The meteors are leftover
debris from Comet Swift Tuttle. To watch a meteor shower you should have a
comfortable chair and a cooler with beverages. Someone special to share the experience
with you is optional. Look to the northeast starting about 10 pm. (If you look low to
the north at 10:03 on the 12th, you will see the International Space Station cross from
Northwest to Northeast.) Moonrise isn’t until after midnight so the skies should be
dark.
There are two full moons in August. The first one is on August 1st and the second full
moon - sometimes referred to as the “Blue Moon” - is on August 31st. There is no
significance to the Blue Moon other than it is the second full moon in the month. Since
there is a full moon every 29.5 days, every month can have a Blue Moon but February.
February will not have a full moon at all in 2018, and that means both January and
March will have two full moons.
Something you may or may not want to know. On June 10th a potentially hazardous
asteroid (2012 LZ1) was discovered by the Siding Spring Observatory in New South
Wales, Australia. 2012 LZ1 was thought to be 500 meters wide and would miss us by
3.4 millions miles on June 14th. We have small asteroids miss us by closer margins
several times each year so 2012 LZ1 wasn’t particularly exciting. However, after it
passed, radar imaging showed the asteroid to be twice as large as the original estimates
- estimates done by light reflection. As it turned out, 2012 LZ1 was a kilometer (.62
miles) wide. An asteroid that large is considered “civilization killing”. Asteroid 2012
LZ1 didn’t come dangerously close to Earth, but it did bring up concerns about why we
didn’t find it until four days before it passed, why did we misjudge its size, and how
could we have prevented it from hitting Earth if it were on a collision course.
Art Maurer
Director -Trackman Planetarium
Joliet Junior College
([email protected] <mailto:([email protected]> )