Planets, planets and less planets Controversy was in full swing this month at the International Astronomical Union meeting in Prague as astronomers struggled to redefine the different types of bodies that circle the sun. The number of new, large objects
Planets, planets and less planets
Controversy was in full swing this month at the International Astronomical Union meeting in Prague as astronomers struggled to redefine the different types of bodies that circle the sun. The number of new, large objects being discovered in the solar system was beginning to pile up, and people needed some way to categorize them. The problem was, once the classifications started it began to tumble out of control. Astronomers quickly realized that redefining the solar system meant the inclusion of potentially dozens, if not hundreds of additional planets added to our solar neighborhood.
Pluto had been going through an identity crises for a number of years now, labeled with a variety of designations from simply a planet to pluton, Kuiper Belt Object or Trans-Neptunian Object. But the recent decision from the IAU ousted it from the exclusive planet club to the lower status of “dwarf planet”— not a very flattering title. Most of us alive today have always known Pluto as a planet and will have to adjust to this new classification.
Fortunately for future school kids, they will now have to memorize only eight planets instead of a dozen or more, and the hope is that we are now aware of the variety of members that make up our solar system. Slowly, the more prominent ones will be added to the textbooks as they get dubbed with official names. (After all, you can’t keep calling dwarf-planet “2003 UB313” and not think of a disease or rock group — even the nickname Xena works for me.)
Coincidentally, as we concentrate on the new objects out there, three of those familiar to us are in our night sky right now. These are the planets you can’t see with just your eyes and are not part of the five “naked eye” planets that were known for thousands of years. If you have a good set of binoculars along with a good sky map you might spot two of them, Uranus and Neptune. The third, dwarf-planet Pluto, will require at least an 8-inch telescope. (For those very new at astronomy, 8-inch describes the diameter of the mirror, not the length of the tube!) Finding these three planets isn’t for the novice observer — you first have to know how to find the constellations they currently reside in with your star map. Neptune is in Capricornus, relatively easy to see in the sky from Hawai‘i, but Uranus is in Aquarius, which is a fairly dim constellation almost impossible to identify from a well-lit city. And Pluto is in a constellation called Serpens, which isn’t exactly a household name since it’s not part of the zodiac.
But this is not to say you shouldn’t try. After all, these planets will soon be joined with others that will be telescopic even at best and most of us will probably never see these new ones with our eyes except on the Internet. The local amateur group Hawaiian Astronomical Society should be able to help — check out their Web site, www.hawastsco.org, and join them in a star party or two. Soon we’ll be referring to Uranus and Neptune as our “close neighbors” at their relative average distance of about two to three billion miles from the sun, compared to those much farther away.
As technology improves, the number of discoveries will grow as well, as is the nature of science. Hopefully this is a good thing for our species as we expand our knowledge of our universe and ourselves.
By the way, the astronomers of the IAU who made this decision about the planets are the same folks with the authority to name stars. Not the Internet company that takes your money and claims that you have now purchased an authentic “star name!” (But that’s another article.)
Hawai‘i once again “shut out” of two eclipses
While we will not be able to view them, it is worth mentioning there will be both a lunar and solar eclipse next month, both on the opposite side of the Earth from Hawai‘i.
On the night of Sept. 7 and 8, a slight partial eclipse of the moon will be visible from Africa, Asia, Australia and Eastern Europe. A couple of weeks later on Sept. 22, an annular solar eclipse will be visible from parts of Guyana, Surinam and French Guiana in South America. Other parts of South America, the Atlantic Ocean and western and southern Africa will experience a partial solar eclipse. An annular solar eclipse occurs when the moon is at apogee, or the farthest point in its oblong orbit around the Earth, and does not fully cover the face of the sun at the peak of the eclipse, instead leaving a thin ring of sunlight around the edge of the moon’s disk. Technically this is a partial eclipse since the sun’s disk remains visible.
The Planets
Mercury
Mercury spends most of the month coming back to the evening sky. In the beginning of September you can’t see it at all as it is behind the sun, but by the second half of the month it may be spotted low in the west after sunset. The sun is setting earlier as we head into fall, so the chances of seeing Mercury after sunset is better.
Venus
Although it is the brightest planet, Venus is rising later and becoming progressively difficult to find right before the sun rises in the east. Even in early September it rises only an hour before the sun and is not high in the sky before it is washed away by the dawn. By the end of September it will rise less than half an hour before the sun and will be more challenging to spot.
Mars
Mars is setting around 45 minutes after the sun in early September and is definitely not going to be easy to view. It is almost opposite in its orbit around the sun from us and is small and dim in the evening sky. Many people who called in response to “that Mars e-mail” were surprised to learn that Mars isn’t big and bright as the e-mail describes but rather the complete opposite!
Jupiter
The giant gas planet still dominates the night sky this month, although it’s starting to set earlier and earlier. By mid-October it will be low in the west and not easy to see unless you have a clear view in that direction. On Sept. 25 and 26, the new moon can be spotted just below and then just above Jupiter. One note: Last month I mistakenly stated that Jupiter spends a month in each constellation of the zodiac. I meant to say one year and thus Jupiter takes approximately 12 years to circle the sun. I am sorry if it caused any confusion.
Saturn
Saturn is first to rise in the morning sky at around 4:45 a.m. in early September and about an hour and a half earlier by the end of the month. There is a waning crescent moon on Sept. 18 just above the ringed planet and just under it the next morning. Saturn rises just at the head of the constellation Leo the Lion.
Questions? Contact Carolyn Kaichi at hokupaa@bishopmuseum.org or (808) 847-8203.
Moon phases
First Quarter: Sept. 30
Full Moon: Sept. 7 (largest of 2006!)
Third Quarter: Sept. 14
New: Sept. 22
All dates are Hawai‘i Standard time.
Bishop Museum Information
Daily Planetarium schedule:
Call (808) 848-4136 or check out our new podcasts at feeds.feedburner.com/bishopmuseum
Daily Observatory schedule:
Open for solar viewing daily from 2:30 p.m. to 3:15 p.m.
Bishop Museum sky information lines
Call (808) 848-4136 for pre-recorded sky information and planetarium schedule.
Bishop Museum Planetarium homepage
www.bishopmuseum.org/exhibits/planetarium/planetarium.html
Bernice Pauahi Bishop Museum, the State Museum of Cultural and Natural History was founded in 1889 by Charles Reed Bishop as a memorial to his wife, Princess Bernice Pauahi Bishop, the last descendant of the royal Kamehameha dynasty.
It is open daily (except Christmas) from 9 a.m. to 5 p.m. Admission is $14.95 for adults and $11.95 for children (4 to 12 years). Children under four are free. Kama‘aina rates are available. The Museum is located at 1525 Bernice Street. For information, call (808) 847-3511.
