CLUB EVENTS:
Celebrate the "World Ceres" in March!
Come to our meeting at Explorit, Saturday March 25 at 7:30 p.m. The topic will be Asteroids, including Ceres, the largest known asteroid. Ceres will be visible with binoculars in the late night and early morning sky as it moves through the constellations Virgo and Coma Berenices.
We will begin the meeting with a slide show on asteroids, what they are, how they differ from planets, how they were discovered, and what we know of their composition and possible origin. Of course, we'll have the latest photos from the space probe NEAR, orbiting the asteroid Eros at a height of 124 miles. If the sky is clear, we will adjourn for some telescopic views of the heavens; if not, we will construct paper models of the NEAR spacecraft. Come join us!
To get your mind in gear for the meeting, here are some
questions about asteroids.
Questions
- When and by whom was the first asteroid discovered?
a) Galileo in 1630; b) Piazzi in 1801; or c) Tombaugh in
1930.
- Are all asteroids named for women?
- Are asteroids the remnants of a planet that existed between
Mars and Jupiter?
- Can an asteroid have its own moon?
- Which is larger: 1 Ceres, or the Moon?
- Which of the following are asteroids: Europa, Ganymede, or
Juno?
- BONUS QUESTION: The median semimajor axis of the orbits of
asteroids is 2.7 au. Hence the sidereal period of revolution (in years) of
the median asteroid is approximately (a) 4.4; (b) 20;(c) 2.7; (d) 7.3 ?
Answers
- Giuseppe Piazzi discovered the asteroid "1 Ceres" 99 years
ago in 1801. He was director of the observatory at Palermo, Sicily.
- The first 8 Asteriods, and many others, were named for
goddesses. The number preceding an asteroid's "official" name refers to the
order of its discovery; hence, Ceres is "1 Ceres." Piazzi named 1 Ceres for the
"goddess of Sicily." Since the mid-19th century, asteroids can be named after
almost anything or anyone. For example, discovery 1971QX2 received the official name "2309 Mr. Spock." The discoverer may suggest a name, but the International Astronomical Union has to agree to make the designation official.
- Asteriods may be the remnants of larger "planetoids" that
collided with each other between the orbits of Mars and Jupiter. How big were
these "planetoids'? If you combined the mass of known asteroids between Mars and Jupiter, it would equal a body only 1/35 the mass of our Moon.
- Yes. Asteroid 243 Ida has a moon called Dactyl, which was
observed by the spacecraft Galileo while on its way to Jupiter. Asteroids 2
Pallas and 12 Victoria have at least one moon each. Asteroid 8 Flora has a mass of at least 13 tiny bodies, 5 of which have diameters of over 18
miles.
- Asteroid 1 Ceres has a diameter of 621 miles, and the
Moon's diameter is roughly 2,160 miles.
- Juno (a.k.a. 3 Juno) is an asteroid, Europa and Ganymede
are satellites of Jupiter. However there are 2 asteroids named for these
mythological figures: 52 Europa and 1036 Ganymede.
- (a) 4.4 years.
[From James A. Van Allen's 924 Elementary
Problems and Answers in Solar System Astronomy (1993)]
February Meeting Report It was another dark and rainy night when approximately 15 members appeared at Explorit for a slide show on "What's Up With Jupiter." We saw a slide show recounting the feisty little spacecraft Galileo's trials and triumphs on its way to Jupiter. We also had a sing along that extolled the exploits of the spacecraft. Songs included Arrival Day (sung to the tune of "Jambalaya on the Bayou") Sunrise, Sunset (concerning Jupiter's 8-hour day), and Will I Still Explore (sung to the tune of "When I'm 64")
The songs,
written by the project members are at:
http://www.jpl.nasa.gov/galileo/songs.html
Outside, the clouds were too dense for star gazing. Maybe next month!
Special Event The Astronomical Association of Northern
California (AANC) is presenting a major symposium on "A Date With the Universe"
from 9:00 a.m. to 5:00 p.m. Saturday March 25 at the California Academy of
Sciences in Golden Gate Park, San Francisco. Topics include astrobiology,
cosmology, adaptive optics, and other events. For more information visit:
http://aanc-astronomy.org
|