honoluluadvertiser.com

Sponsored by:

Comment, blog & share photos

Log in | Become a member
The Honolulu Advertiser
Posted on: Sunday, July 29, 2007

Hawaii will see a rare total lunar eclipse Aug. 27

By Carolyn Kaichi
Bishop Museum

Space will be a very busy place in August, in astronomical terms as well as space exploration activities.

One of the highlights is that Hawai'i will see a rare total lunar eclipse on Aug. 27.

While lunar eclipses are not as rare as solar eclipses in terms of the area affected (and how many people are able to view it), a total lunar eclipse is still not something we see every day.

First, some eclipse basics. Remember that a lunar eclipse is defined as the moon being inside the shadow of Earth as the sun, Earth and moon all line up.

Normally we see the moon as a slivery reflection of sunlight — the moon otherwise appears dark since it doesn't generate its own light.

As the moon goes around the Earth every month, we see the different phases as the moon is lit up from different angles.

We don't have lunar eclipses every month however, because the moon doesn't lie on the exact plane of the Earth's orbit around the sun, but rather is offset about 5 degrees.

So most of the time the moon, Earth and sun miss that critical lineup and no eclipse takes place. Lunar eclipses occur on average two to four times a year.

There are three types of lunar eclipses: a subtle penumbral shadow, the varied characteristics of a partial eclipse and the more dramatic total lunar event we will see in August.

The last time we had the opportunity to view a total lunar eclipse was in 2003, but the moon was just rising at dusk in the last stages, which made it difficult to experience the full effect.

Although the moon is in Earth's shadow during the eclipse, sunlight still reaches the moon's surface indirectly as it's refracted, or bent by the Earth's atmosphere. Blue light gets filtered out and the leftover red light reaches the moon. Depending on atmospheric conditions, the resulting effect is a significant dimming to a deep reddish tint.

August's total lunar eclipse will occur at full darkness with the moon almost directly overhead, and Hawai'i will be able to view the entire event, starting from the partial phase through totality.

The Bishop Museum will have a special public program featuring scientists from the University of Hawai'i, from 9:30 p.m. until the start of totality at 11:50 p.m.

Lectures will be held in both in the planetarium and the Science on a Sphere rotunda.

The guest scientists will talk about eclipse basics, research on the moon and future exploration involving the moon.

Members of the Hawaiian Astronomical Society will be on the grounds to provide closeup views of the moon and expertise on the eclipse as it progresses until 1:30 a.m. the next morning.

As an added attraction, local geocachers have planned a geocaching event on the grounds of the Bishop Museum during the eclipse.

Geocaching is a treasure hunt of sorts that uses portable GPS units to give clues to finding objects. See www.geocaching.com for more information on geocaching.

Admission to the Bishop Museum eclipse night is $3; members get in free.

Another astronomical event of note is the Perseid meteor shower, peaking on Aug. 12.

This year is predicted to be very favorable, with the moon in a new phase. That means the sky will be nice and dark if you find a place without too many artificial lights.

The best time to look for the meteors is after midnight.

PHOENIX MARS MISSION READY TO LAUNCH

NASA launches its new Phoenix Mars Lander mission in August.

Unlike the robotic rovers now moving about the Martian equator, Phoenix will be a stationary "laboratory" planted on the frozen northern plains of the Red Planet.

While the Mars rovers have only found evidence of water, Phoenix will actually study water ice that exists in the polar regions of Mars, taking samples of the Martian soil for analysis right there on the lander.

Phoenix is the first in a series of NASA Scout missions to Mars — smaller scale, relatively cheaper missions targeting specific sites on Mars for study and "scouting" the way for future human exploration.

Finally, the space shuttle takes off again in August as construction continues at the international space station.

This time, the Endeavour will carry the first educator-astronaut, Barbara Morgan, into space. Unlike the Teacher in Space program (teacher Christa McAuliffe flew aboard the Challenger that exploded during its launch in 1985), educator-astronauts are fully trained as working crew members but also specialize in connecting space exploration to students of all ages.

THE PLANETS

Mercury: Mercury rises at least an hour before sunrise in early August, but by the end of the first week it's already getting very close to the sun.

If you want to try to catch the quick planet during the first few days, get up very early (by 5:30 a.m.) and look toward the east if you have a clear view to the horizon.

Venus: Say goodbye to the brightest planet until it emerges in the morning sky later in the month.

Venus is in conjunction with the sun on Aug. 18 but reappears in the morning sky about a week later.

It will be almost another full year before we see Venus as an evening planet again.

Mars: Mars is up in the east early in the month, close to the Pleiades star cluster.

During the month the red planet slowly creeps toward Taurus, becoming the other "eye" of the bull around Aug. 20-23.

This is a good time to compare the color and brightness of the starry eye of Taurus, Aldebaran, to the planet Mars. While almost the same color, Mars is the brighter of the pair, as it is getting closer to the Earth.

By the end of the month Mars rises a little after midnight, tucked between the horns of the bull.

Jupiter: Although Jupiter has some company in the first week of the month, it will be the only visible planet in the evening throughout the month.

After midnight it is joined by Mars but Jupiter will be low in the west by the time Mars rises in the east.

The largest planet is very bright and sits to the west of Antares, the heart of the constellation Scorpius.

Saturn: Saturn is all but out of the picture in the evenings after the first few days of August. If you have a clear view to the west, you may be able to spot the little yellow light low in the western sky after sunset near Venus.

Saturn is in conjunction with the sun on Aug. 21 and will reappear in the morning sky ahead of the sun by the middle of September.

MOON PHASES

Third quarter: Aug. 5

New moon: Aug. 12

First quarter: Aug. 20

Full moon: Aug. 28

• • •