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With the naked eye, the maximum number of stars you can
see in the sky at one time is about 2,500. As the earth rotates,
different stars come into view, totaling about 8,000 viewable stars in one complete
earth rotation. As hard as it is to believe, all of these viewable stars
are within our own Milky
Way galaxy. The other 200 million stars in our Milky Way, and the trillions beyond, can only be seen with the aid of binoculars or a telescope.
The more powerful the telescope, the more stars we can see.
It's staggering to realize that there are hundreds of billions of galaxies
like our Milky Way with hundreds of billions of stars each. The
universe being so incredibly vast, measuring
distances in miles requires too many zeros
to be practical. So
distances in space are measured in light years (the distance
light travels in one year). Since light speeds along at 186,000 miles per
second, it travels 6 trillion miles in one year. So a light year is 6
trillion or 6,000,000,000,000 miles.
To relate to the vast distances in space, consider
that:
(1) A Space Shuttle traveling at 18,000 mph (5 miles per second) would take
333 million years to reach our nearest star, 4 light years
away.
(2) The two
Voyager spacecraft, launched in
1977 to photograph the outer planets of Jupiter, Saturn, Neptune and Uranus, traveling at 35,000 mph, are just now leaving our
own solar system, 35 years later!
(3) If you could build a spaceship
capable of traveling at the speed of light
(37,000 times faster than a Space Shuttle),
look how long it would still take you to travel to the following places:
You could circle the earth 7 times in 1 second.
You could reach the moon in 2 seconds.
You could reach Mars in 3 minutes.
You could reach the Sun in 9 minutes.
You could reach Jupiter in 1 hour.
You could reach Pluto in 4 hours.
You could reach the nearest star in 4 years (within
in our own Milky Way galaxy).
You could travel across our Milky Way galaxy in 150,000 years.
You could reach our neighbor
galaxy, Andromeda, in 2.3 million
years.
It would take many trillions of years to cross the known universe.
And all that at 186,000 miles per
second, or 670 million miles an hour!
MORE ABOUT OWN MILKY WAY GALAXY
This photo
shows where our own sun is located in
the Milky Way galaxy.
The name Milky Way comes from the fuzzy band in the clear night sky (see
photo below) that can be see from Earth,
but only in areas where the night sky is not polluted by city lights. The Milky Way was discovered by the
ancient Greek philosopher Democritus, who was the first person to assume
that the Milky Way existed and was made up of billions of distant stars. The
Milky Way is believed to be more than 13 billion years old, which is
estimated to be virtually as old as the entire universe itself. The Milky
Way galaxy has a whopping circumference of roughly 250 to
300 thousand light
years and contains 200 to 400 billion stars. The Earth’s solar system is
believed to exist very close to the Galaxy’s galactic plane, due to the fact
that the Milky Way essentially divides the night sky into two virtually
equal hemispheres. Scientists now estimate that in roughly three billion
years, the Milky Way galaxy will collide with the Andromeda Galaxy, which is
slowly working its way towards us at a speed of about
66,000 miles per hour.
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Have you ever seen the band of our Milky Way Galaxy? It
is much more visible when
viewed in a location away from the glare of city/suburban lights. In a clear sky from
a
dark location at the right time, a faint band of light becomes visible across the
sky.
Soon after your eyes become adapted, you should be able to spot the fuzzy
band
that contains billions of stars and is the disk of our own Milky Way galaxy.
Since we
are inside this disk, the band appears to circle the Earth. Visible in the
above image,
high above in the night sky, the band arcs. The bright spot just
below the band is the
planet Jupiter. This photo was taken from a mountaintop in
Hawaii. |
