"Planet Earth, with all its wide expanses, deep
seas, and massive mountains, amounts to a speck of dust when stacked up against
the immensity of the cosmos. Some of the tiny pin prints of light we see from earth are actually stars big enough to swallow our entire solar system."|
How big? How far? How fast?
There are 100 billion galaxies in the observable part of the universe. Each galaxy has billions of stars.
The earth orbits the sun about 66,000 miles per hour.
Planet Earth, with all its wide expanses, deep seas, and massive mountains, amounts to a speck of dust when stacked up against the immensity of the cosmos.
The human mind is finely tuned to deal with the scale of every day experience. The brain can understand traveling 50 miles in a day, but what about 500,000? A person might know what it's like to move at 100 mph, but what about 100 million mph?
Numbers like millions, billions, and trillions are very hard for most of us to imagine because most of us don't have billions or trillions of anything.
How can we ever know the universe if our brains can't really comprehend its colossal size? Scale models help scientist and astrologist to get a better understanding of the size of the universe.
R136a is a young star, about 1 million years old. It's between 250-300 times the mass of our sun. A neutron star is the left over core of a super-nova explosion, with its mass packed astoundingly tight. The density of a neutron star is the equivalent of 10 million monster trucks packed down to the size of a sugar cube. Stack the 10 million monster truck sugar cubes 10 miles high and 10 miles wide, and that's the size, mass, and volume of a neutron star.
Some of the tiny pin prints of light we see from earth are actually stars big enough to swallow our entire solar system. Can the human mind comprehend the largest star in the galaxy?
The sun is the biggest object in our solar system. In terms of sheer mass, it weighs over 300,000 times more than the earth. In terms of volume, it's also the largest object at 800,000 miles across. It's 109 times as wide as the earth, which means that over a million earth's could fit inside the volume of the sun.
As enormous as the sun is in earthly terms, our home star is miniscule compared to our galaxies lineup of stellar mammoths.
Adhara, aka, Epsilon Canis Majoris, Canis Majoris is a constellation whose name translates as the "Great Dog." Epsilon Canis Majoris is 17 times wider than the sun and is 430 light years away. It sits in the same constellation as Sirius, the brightest star in the sky.
Dubhe is almost twice the size of Epsilon Canis Majoris and is a giant star on the lips of the big dipper. It's 120 light years away and is called the Red Giant because of its orange color.
Aldebara is a giant red star, in Taurus the Bull, about 65 light years away. Betelgeuse (pronounced bettlejuice) is 650 light years away and 1000 times the size of the sun. If Betlegeuse were in our solar system, all 8 planets would either be destroyed or too hot to be habitable.
VY Canis Majoris is 2000 times the diameter of our sun. It would take a commercial airplane about 1200 years to fully circle it.
Distances in the universe are unimaginably vast. To get an understanding of the size, look at the 870,000 miles of the diameter of the Sun. View it in terms of the size of a bowling ball. Our earth would be a tiny bead in size compared to the size of our Sun.
This far out, a planet takes a long time to do an orbit around the sun. The Neptunian year is about 165 earth years. Only one has passed since the discovery of Neptune.
If the space between the planets in our solar system strains human comprehension, then the vast distance between stars and galaxies totally overwhelm us. The distances are so immense, the questions of "How big?" and "How far?" are questions that challenge anyone's power of comprehension. The magnitudes of the universe also extend to speed. Scientist have discovered that the universe is a super-velocity race track whose giant planets move faster than speeding bullets.
To determine the speed of the universe we must first understand the celestial measuring stick known as the "light year." One light year is the distance light travels in one year. This amounts to about 6 trillion miles, or 186,000 miles per second. That's equivalent to light bouncing back and forth between Los Angeles and New York, 38 times in one second. 1,670 miles per second, and there is nothing on Earth that compares. An F15 can reach Mach 2.5, or 1500 mph.
What this astronomical speed (186,000 miles per second) means is that much of the cosmos is moving at speeds we cannot fully comprehend. Motion is actually the normal state of affairs in the universe. We may think we are standing still, and we are relative to the ground, but Earth is orbiting the Sun; the Sun is orbiting around the center of our galaxy - the Milky Way - our galaxy is orbiting our local group of galaxies; and all of these objects are moving at extremely high speeds. The earth is orbiting the Sun at a speed of roughly 66,000 miles per hour.
The Milky Way spans 100,000 light years across. The next galaxy over, Andromeda, is approximately 25 times the size of the Milky Way.
The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts. The Andromeda Galaxy is the nearest spiral galaxy to our Milky Way galaxy, but not the closest galaxy overall. It gets its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. The Andromeda Galaxy is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies.
How Long is a Light-Year?
When the Universe was young, it
was nearly smooth and featureless. As it grew older and developed, it became
organized. We know that our solar system is organized into planets (including
the Earth!) orbiting around the Sun. On a scale much larger than the solar
system (about 100 million times larger!), stars collect themselves into
galaxies. Our Sun is an average star in an average galaxy called the Milky Way.
The Milky Way contains about 100 billion stars. Yes, that's 100,000,000,000
stars! On still larger scales, individual galaxies are concentrated into groups,
or what astronomers call clusters of galaxies.
The cluster includes the galaxies and any material which is in the space between
the galaxies. The force, or glue, that holds the cluster together is gravity --
the mutual attraction of everything in the Universe for everything else. The
space between galaxies in clusters is filled with a hot gas. In fact, the gas is
so hot (tens of millions of degrees!) that it shines in X-rays instead of
visible light. In the image above, the hot X-ray gas (shown in pink) lying
between the galaxies is superimposed on an an optical picture of the cluster of
galaxies. By studying the distribution and temperature of the hot gas we can
measure how much it is being squeezed by the force of gravity from all the
material in the cluster. This allows scientists to determine how much total
material (matter) there is in that part of space.
There is currently much ongoing research by scientists attempting to discover exactly what this dark matter is, how much there is, and what effect it may have on the future of the Universe as a whole.
Dark Matter and Dark Energy, makes up three-fourths of all
matter and energy in the universe, a universe that is expanding and accelerating
outwards. This virtually unknown matter, accounts for a large part of the total
mass in the universe. It is estimated to constitute 84% to 96% of the matter in
the universe. The consensus among cosmologists, is that dark matter is composed
primarily of a not yet characterized type of subatomic particle.
You will not see the Leafcutter ant if you walk into the massive Amazon rainforest just as we don't see dark matter; but without it, there would be no universe.