|
Our Earth is
located in the Milky Way galaxy and the only stars you can see with the
naked eye are in our own galaxy. To see farther, you need binoculars or a
telescope. Our nearest neighbor, the Andromeda Galaxy is 2 million
light-years away. And there are hundreds of billions of galaxies
(with hundreds of billions of stars each) that are over a million times
farther than Andromeda. Since the Universe is so incredibly vast, measuring
distances in miles would require too many zeros
to be practical. So
distances in space are measured in light years, which is the distance that
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 speed of light, consider this: Our fastest rockets travel
at 25,000 miles per hour. The speed of light is 26,000 times faster than
that. So if you built a spaceship that could travel at the speed of light,
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 trillions of years to cross the known universe.
And all that at 186,000 miles per
second! Difficult to conceive, isn't it?
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 seen from Earth. 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 250-300 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 1,100 miles per
minute.
|
|
Have you ever seen the band of our Milky Way Galaxy? 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. |
