HOW FAST IS EARTH
MOVING THROUGH SPACE?
To begin with, Earth is rotating on its axis at
the familiar rate of one revolution per day. For those of us living at Earth's midlatitudes -- including the United States,
Europe, and Japan -- the rate is almost a thousand miles an hour. The rate is higher at the equator and lower at the poles.
In addition to this daily rotation, Earth orbits the Sun at an average speed of 67,000 mph, or 18.5 miles a second.
Perhaps that seems a bit sluggish -- after all, Mars Pathfinder journeyed to Mars at nearly 75,000 miles per hour. Buckle
your seat belts, friends. The Sun, Earth, and the entire solar system also are in motion, orbiting the center of the Milky
Way at a blazing 140 miles a second. Even at this great speed, though, our planetary neighborhood still takes about 200 million
years to make one complete orbit -- a testament to the vast size of our home galaxy.
Dizzy yet? Well hold on. The
Milky Way itself is moving through the vastness of intergalactic space. Our galaxy belongs to a cluster of nearby galaxies,
the Local Group, and together we are easing toward the center of our cluster at a leisurely 25 miles a second.
If
all this isn't enough to make you feel you deserve an intergalactic speeding ticket, consider that we, along with our cousins
in the Local Group, are hurtling at a truly astonishing 375 miles a second toward the Virgo Cluster, an enormous collection
of galaxies some 45 million light-years away.
As Vinnie said: "Don't worry about it."
WHY DO
PLANETS CHANGE POSITION IN THE NIGHT SKY?
Are they catholic? No, but
seriously, the planets appear to change position against the "fixed" stars in the night sky because of the relative
motion of both Earth and the planets as we all move along in our orbits around the Sun. The swift-moving inner planets Venus
and Mercury can move from morning to evening appearances and back again in as little as a few months. The giant outer planets
such as Jupiter or Saturn, with orbits taking decades to complete, appear to move more slowly against the background of stars.
WHAT IS A RED GIANT?
A state of stellar
evolution beyond the main-sequence life of a star. A red giant core is degenerate ionized helium, surrounded by a shell of
hydrogen fusion, that expands the outer atmosphere in response to higher core temperatures. The hydrogen fusing shell eats
through the surrounding atmosphere and deposits helium onto the shrinking core. The ballooning atmosphere cools and glows
red; hence red giant. The Sun will become a red giant the size of Earth's orbit in five to six billion years. Once the helium
core reaches 100 million degrees, it explosively begins fusing helium. The birth of the active helium core is called the helium
flash. The Sun as a red giant will fuse helium for about 2 billion years after the helium flash.
WHAT IS A BLACK HOLE?
An object with such powerful gravity that nothing can escape
from it, including light. The black hole's mass is concentrated in a point of almost infinite density called a singularity.
At the singularity itself, gravity is almost infinitely strong, so it crushes normal space-time out of existence. As the distance
from the singularity increases, its gravitational influence lessens. At a certain distance, which depends on the singularity's
mass, the speed needed to escape from the black hole equals the speed of light. This distance marks the black hole's "horizon,"
which is like its surface. Anything that passes through the horizon is trapped inside the black hole. Black holes come in
several varieties, depending on mass.
OTHER COOL QUESTIONS!
HOW DID THE CONSTELLATIONS GET THEIR
NAMES?
Most constellation names are Latin in origin, dating from the Roman empire, but their meanings often originated
in the distant past of human civilization. Scorpius, for instance, was given its name from the Latin word for scorpion, but
ancient Egyptian hieroglyphs from before 3000 B.C. refer to the star group as "Ip," the scorpion king. Orion, the
hunter, bears a Greek name, but had been seen as a hunter-hero figure since the times of ancient Babylon.
WHAT
ARE METEOR SHOWERS?
An increase in the number of meteors at a particular
time of year is called a meteor shower.
Comets shed the debris that becomes most meteor showers. As comets orbit
the Sun, they shed an icy, dusty debris stream along the comet's orbit. If Earth travels through this stream, we will see
a meteor shower. Depending on where Earth and the stream meet, meteors appear to fall from a particular place in the sky,
maybe within the neighborhood of a constellation.
Meteor showers are named by the constellation from which meteors
appear to fall, a spot in the sky astronomers call the radiant. For instance, the radiant for the Leonid meteor shower is
located in the constellation Leo. The Perseid meteor shower is so named because meteors appear to fall from a point in the
constellation Perseus.
HOW CAN I BEST VIEW A METEOR
SHOWER?
If you live near a brightly lit city, drive away from the glow of
city lights and toward the constellation from which the meteors will appear to radiate.
For example, drive north to view the Leonids. Driving south may lead you to darker skies, but the glow will
dominate the northern horizon, where Leo rises. Perseid meteors will appear to "rain" into the atmosphere from the
constellation Perseus, which rises in the northeast around 11 p.m. in mid-August.
After
you've escaped the city glow, find a dark, secluded spot where oncoming car headlights will not periodically ruin your sensitive
night vision. Look for state or city parks or other safe, dark sites.
Once
you have settled at your observing spot, lay back or position yourself so the horizon appears at the edge of your peripheral
vision, with the stars and sky filling your field of view. Meteors will instantly grab your attention as they streak by.
HOW DO I KNOW THE SKY IS DARK ENOUGH TO SEE METEORS?
If you can see each star of the Little Dipper, your eyes have "dark adapted,"
and your chosen site is probably dark enough. Under these conditions, you will see plenty of meteors.
WHAT SHOULD I PACK FOR METEOR SHOWER WATCHING?
Treat
meteor watching like you would the 4th of July fireworks. Pack comfortable chairs, bug spray, food and drinks, blankets, plus
a red-filtered flashlight for reading maps and charts without ruining your night vision. Binoculars are not necessary. Your
eyes will do just fine.
"KEEP LOOKING
UP!"
Rose Marie's
Website www.SassieCat.com
"Imagination
is more important than knowledge. Knowledge is limited; Imagination encircles the world."
-Einstein
EXPLORE YOUR OWN SPACE/LIFE IDEAS
COSMIC ANCESTRY SPACE SCIENCE ASK AN ASTRONOMER LINEAR? WHAT'S THAT?
"Keep looking up."
LINEAR? WHAT'S THAT??
"Nothing
can be more contrary to religion and the clergy than reason and common sense."
-Francois
Marie Arouet "Voltaire", French author and playwright
www.Techno-Geeks.org
