Update: August 29, 2007

ECLIPSES AND VOYAGES

By Pam Eastlick for THE DEEP on line

Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.

There will be a total lunar eclipse over the Marianas Islands tonight and it occurs in prime evening time.  Eclipses of the Sun and Moon occur when they are exactly lined up with Earth.  This doesn’t happen at every new and full Moon because the Moon’s orbit is tilted 5 degrees to the Earth’s orbit around the Sun. A lunar eclipse or an eclipse of the Moon can occur only at full Moon when the Earth, Sun and Moon are lined up with the Earth in the middle.  The Moon enters the Earth’s shadow and is somehow changed in appearance.

They will see this eclipse in the mainland US, but it occurs in the wee small hours of the morning before dawn.  To view this eclipse from the Marianas all you have to do is go outside tonight and look.  Watch the sunset tonight at around 6:25 p.m.  Then turn completely around and face east (opposite the Sun).  When the Moon rises in the east at 6:29 p.m.; the eclipse will already be underway and the Moon will be about halfway into the penumbra, the lighter part of the Earth's shadow, when it rises.  By 6:51 p.m., the moon will be completely within the penumbra and will begin to enter the umbra, the darkest part of the shadow.  By 7:52 p.m., the moon will be completely in the umbra.  Mid-eclipse, when the moon will appear darkest occurs at 8:37 p.m. tonight.  The umbral or total eclipse ends at 9:21 p.m. and the moon will completely leave the Earth's shadow at 10:22 p.m.

What will the Moon look like?  I'm afraid I can't tell you.  You can still see the Moon in a lunar eclipse because the Earth’s air bends the Sun’s light around the Earth to shine on the Moon.  Lunar eclipses never look the same way twice because the Moon's appearance depends on the quality of Earth's air.  If there's a lot of dirt and volcanic ash in the atmosphere, the moon will be very dark.  In the total lunar eclipse of June 1993, the Moon was barely visible because the eruption of Mt. Pinatubo two years earlier had filled our upper atmosphere with dust, ash and sulfur dioxide.

If Earth’s air is clean, the moon will appear coppery red because it’s being painted with all the colors of Earth’s sunrises and sunsets.  The September 1997 lunar eclipse was much brighter than the one in 1993 and the moon was a definite coppery red.  Unfortunately, that eclipse occurred in the very early morning here on Guam, and not too many people saw it.

Although you may want to go out and view this astonishing spectacle, you may be from a culture that views lunar eclipses as causing problems for pregnant women.  Having the Moon turn blood-red worried the people of many ancient cultures.  Although there is no scientific basis for these beliefs, they are deeply ingrained in many Asian societies.

No matter what your cultural beliefs, watching a lunar eclipse in real time is rather like watching paint dry and this eclipse is perfectly timed to be your ‘commercial eclipse’.  Every time there’s a TV commercial tomorrow night, go out and see how the Moon has changed.  Take the whole family and watch celestial mechanics in motion.  Enjoy!

The Little Robots that Could

One of the wonderful things about life on Earth in the 21st century is space exploration off the Earth.  Although I get frustrated at the bureaucracy that holds us back, we have still put spacecraft on Mars and Venus and having robots that orbit the Earth and the Sun and tell us all sorts of wonderful things.  And the all-time champions of human space exploration are celebrating significant anniversaries.

Alan Stern, a NASA administrator said "It's a testament to Voyager's designers, builders and operators that both spacecraft continue to deliver important findings more than 25 years after their primary mission to Jupiter and Saturn concluded."

Originally designed as a four-year mission to Jupiter and Saturn, the Voyager tours were extended because of their successful achievements and a rare planetary alignment.  The two-planet mission eventually became a four-planet grand tour.  After completing that extended mission, the two spacecraft began the task of exploring the outer heliosphere.

During the first 12 years of their epic journeys, the Voyagers made detailed explorations of Jupiter, Saturn, and their moons, and made the first (and so far only) close-up explorations of Uranus and Neptune.  These marvelous robots returned images of things that human eyes had never seen before as well as scientific data.  They made fundamental discoveries about the outer planets and their moons.  The spacecraft revealed Jupiter's turbulent atmosphere, which includes dozens of interacting hurricane-like storm systems, and erupting volcanoes on Jupiter's moon Io.  They also showed waves and fine structure in Saturn's icy rings from the tugs of nearby moons.

For the past 18 years, the Voyager twins have been probing the outer limits of the solar system.  Although we say that Earth is in ‘outer space’; we’re wrong.  The diameter of our parent star, the Sun, is conventionally given as around 800,000 miles, but that’s misleading.  Our Sun not only emits energy, it also emits particles.  The Sun’s physical boundary actually extends far beyond the orbit of Neptune.  The solar system is full of the Sun. 

After 30 years of travel, the Voyagers are approaching the heliopause, the actual edge of the Sun.  Voyager 1 currently is the farthest human-made object.  It’s around 9.7 billion miles from the Sun.  Voyager 2 is about 7.8 billion miles away. 

In December 2004, Voyager 1 began crossing the solar system's final frontier.  Called the heliosheath, this turbulent area, approximately 8.7 billion miles from the Sun, is where the solar wind slows as it crashes into the thin gas that fills the space between stars.  Voyager 2 could reach this boundary later this year, putting both Voyagers on their final leg toward interstellar space.

Each spacecraft carries five fully functioning science instruments that study the solar wind, energetic particles, magnetic fields and radio waves as they cruise through this unexplored region of deep space.  The Voyagers are too far from the Sun to use solar power.  They run on less than 300 watts, the amount of power needed to light up a bright light bulb.  Their long-lived radioisotope thermoelectric generators provide the power.

The Voyagers call home via NASA's Deep Space Network, a system of antennas around the world.  The spacecraft are so distant that commands from Earth, traveling at light speed, take 14 hours one-way to reach Voyager 1 and 12 hours to reach Voyager 2.  Each Voyager logs approximately 1 million miles per day.

Each of the Voyagers carries a golden record that is a time capsule with greetings, images and sounds from Earth.  The records also have directions on how to find Earth if the spacecraft is recovered by something or someone.

The Voyagers are heading out there.  Since a body in motion remains in motion unless acted on by an outside force and forces are few and far between in the infinite deep beyond the heliopause, the Voyagers will probably voyage literally forever.  As Buzz Lightyear would say “To infinity and beyond!”
I wish the most durable energizer bunnies in the solar system Godspeed as they sail forth among the stars.  I hope someday humans join them!