Download 1 Our place in space

The Universe
http://www.cfa.harvard.edu/seuforum/opis_tour_earth.htm
William Herschel Telescope,
EARTH
La Palma.
These are immense regions of dust
and gas from which new stars are
continually born.
Our Milky Way galaxy is huge: On the scale of the drawing
at upper left, the whole solar system -- Earth, Sun, and
planets -- would be smaller than an atom!
THE NEAREST STAR IS OUR SUN
The sun is five billion years old. But within another five billion
years, the Sun's nuclear furnace will begin to cool.
Most stars are part of "multiple star systems" — two or more
stars that orbit each other. If we lived near a more typical star, we
might see several suns in the sky!
THE SOLAR SYSTEM
ORBITS: SPACE- TIME
'NEARBY' STARS
Lagoon Nebula
A new generation of stars is being
born from enormous clouds of dust
and gas, some 5000 light-years from
Earth. They form when these huge
amounts of matter collapse under
their own gravity.
The next nearest stars are incredibly far away. Even at the speed of
light, it would take about 5 years to reach the nearest star. (Today's
fastest spacecraft would take about 100,000 years.)
New measure of distance: the light-year, the distance
that light travels in one year -- about 9 trillion km.
OTHER UNITS
OTHER UNITS
1 Aau (Astronomic al Unit) = The distance from the earth to the sun is about 93,000,000 miles.
Putting this unit to a scale of 1 AU = 1 inch the distance to the planets from the sun would be:
Mercury .39 inches
Venus .72 inches
Earth 1.0 inch
Mars 1.5 inches
Jupiter 5.2 inches
Saturn 9.6 inches
Uranus 19.3 inches
Neptune 30.2 inches
Pluto 39.9 inches (1 m=3.6 Billion miles)
Nearest star = approximately 4 light years = approximately 63,255 x 4 = 253,022 AU's = 4 miles
away!
Consider you wanted to map our galaxy, making a map where the earth was on inch from the
sun would require a piece of paper the size of the United States to show the "neighborhood" stars.
Even then the problem of finding the earth would be enormous. Remember 93,000,000 miles is 1
inch, this would mean the earth would only be 43 millioneth's of an inch wide on this paper, or
about the size of a large molecule. If drawn to scale the earth on this map would be invisible to
the naked eye.
OTHER UNITS
Using this scale it becomes clear how difficult if would be to
map and navigate in space. Given a scale that would make the
earth larger, the map would become bigger than the entire
planet. Making a map with a greater scale the earth would
disappear from even microscopic measurement.
The term lost in Space is easy to understand when you use
these figures. No proportion or scale is possible as a realistic
and accurate measure of distances in space. In simple terms
the numbers are too astronomical!
OUR GALAXY
Cluster of stars in the Sagittarius Star Field, near the
center of our galaxy. The field of view is about 13
light-years wide.
Closer to the center of our galaxy, stars are packed much closer
together. If you visited this ancient cluster of stars, some 25,000
light-years from Earth, the night sky would shine with thousands of
times more stars than we see from Earth.
GALAXIES BEYOND OURS
Andromeda
galaxy
Far beyond our own Milky Way galaxy lies the spiral galaxy Andromeda, one of our nearest
neighbor galaxies. The billions of stars in this galaxy are each too faint to make out - but
their combined light forms a beautiful swirl typical of many galaxies. This is probably what
our own Milky Way galaxy would look like if we could take an image of it from the outside.
The individual stars in this image (white dots) are part of our own Milky Way galaxy and are
much closer than Andromeda.
It takes 2 million years for light from the Andromeda galaxy to reach Earth, making it the
furthest object you can see with your naked eye.
THE UNIVERSE FILLED WITH GALAXIES
The cluster of galaxies, Abell 1689, lies 2
billion light-years from Earth in the
constellation Virgo
Here is the view 2 billion light-years from Earth - about a
thousand times further than our neighboring galaxy,
Andromeda. All but two objects in this image are galaxies,
each of which contains billions of stars. Amazing the
immensity of the universe!
Lying 800 million light-years from Earth, this cluster of
galaxies is engulfed by an enormous cloud of gas revealed
here by a telescope that detects x-rays (colorized blue so we
can see it). Giant clouds like this are among the largest
structures in the universe (just the tip of an unseen iceberg).
Even more matter, believed to be invisible to all telescopes,
has been detected tug on surrounding galaxies.
DEEP SPACE
The Hubble "Ultra Deep Field" shows a tiny patch of
sky in the constellation Fornax, just below Orion.
Looking out in space is looking back in time
The light from the closest of these galaxies has taken about 6 billion years to reach
us - and the furthest more than twice that long. So we are seeing this part of the
universe not as it looks now, but as it looked as many as 12 billion years ago. The
telescope is a kind of time machine; it lets us see our distant past.
These ancient galaxies are not yet fully formed - and their colors have been
distorted by the expansion of the universe. A study of images like these may yield
clues to the origin of galaxies and of the universe itself.
EVEN FURTHER
Most distant galaxies
(X-Rays)
The universe is much larger than what we can observe, but light from
the most distant galaxies has not yet had time to reach us since they
were first formed.
This image taken from space, shows what may be the most distant
(and ancient) galaxies we can see. The dots are thought to be x-rays
emitted by enormously powerful black holes at the centers of
galaxies that are just beginning to form. In fact, the galaxies may not
yet contain stars that have begun to shine — or they may be so
distant that their starlight has been absorbed by dust.
THE FURTHEST WE CAN SEE
Baby universe
This view of almost the entire night sky is the furthest light we can see. It is also
the oldest: The light was emitted shortly after the Big Bang, and has been
traveling through space for 13.7 billion years. When first emitted, this light was
blindingly bright, but during its long journey to Earth it lost most of its energy;
It can only be detected by specialized radio telescopes.
In this "baby picture" of the universe, the red and yellow patches are regions that
are just a few millionths of a degree hotter than the blue and black areas. This
tiny difference helped seed the formation of galaxies out of the shapeless gas that
filled the early universe.
INTERESTING LINKS
http://solarsystem.nasa.gov/index.cfm?Display=Flash
http://map.gsfc.nasa.gov/universe/universe.html
http://map.gsfc.nasa.gov/resources/imagetopics.html
http://www.essortment.com/in/Science.Astronomy/index.htm
http://www.history.com/shows/the-universe/interactives/interactiveuniverse