| Melissa: | What's this got to do with education? |
| Liao: | Everything – until we understand our place in the heavens, we cannot comprehend our place on earth. |
ASTRONOMY 101:
a short summary by T Newfields
Sirius, the brightest “star” when seen from Earth is actually a binary system.
The distance between Sirius A and B is comparable to the distance between Sol and Uranus.
Alpha Centauri C, the nearest star to our sun, is too dim to for the naked eye, yet a mere 4.22 light years away.
It’s a red dwarf (M5.5Ve) only one-tenth as massive as Sol.
There are 10 stars within 10 light years of our sun. Within 100 light years, more than 500 type-G stars are known.
Within 1000 light years, perhaps a million stars exist. A mere 20 light years from us, a planet which has liquid water
(though 5 times Earth's gravity) has been already ascertained.
This galaxy, 100,000 light years across and a thousand light years wide, has about 200-400 billion stars as well as a black hole eating at its center.
The nearest galaxy, Andromeda, is 2.2 million light years away and the only object in the sky visible to the naked eye beyond the Milky Way.
The Andromeda galaxy is approaching us at 100 to 140 kilometers per second and is expected to collide with our galaxy in another 3 or 4 billion years.
Only half-a-billionth of the energy released by the sun ever reaches the Earth.
On the other side of our galaxy, about 45,000 light-years from Earth, is a star (LBV 1806-20) shining 40 million times more brightly than the Sun.
That star will hypernova in a few million years.
A billion years ago a day on Earth lasted about 18 hours and one lunar orbit was merely 20 days. As a consequence of friction and gravitational pulls,
our planet’s rotation is gradually slowing at the rate of 2.2 seconds per 100,000 years. The moon is also moving away from the Earth about 3 cm per year.
Some 19,000 meteorites (weighing 6 tons in total) hit the Earth each day. Most of them burn up in the atmosphere.
Once every thousand years or so a meteorite large enough to destroy a city impacts Earth.
Once ever 250,000 years or so one large enough to impact the global climate drops by.
Fortunately for us, Jupiter attracts many of the meteorites within our solar system.
If the Earth were the size of an apple, its atmosphere would be even thinner than an apple's skin.
At this point in time humans have no impact on our planet's mantle or core, but collectively we do influence its atmosphere.
About 99.85 % of the mass of our solar system is contained in the Sun itself. Jupiter, the fifth planet, has more mass the all other planets combined.
If the Earth were the size of a dot, the Sun would be a giant grapefruit. Keep this in mind when your problems feel “big” . . .
Each of these facts in isolation might seem rather ordinary – but taken together they point out an extrordinary set of conditions.
