Astronomy (Lecture 1) Luke MacKenzie
- Mostly vacuum (empty space)
- Everything we can possibly see is a tiny fraction
The Sun is Our Star:
- massive ball of glowing gas that generates energy through nuclear fusion
- 100x as wide as the Earth
- source of almost all energy on Earth
Planets:
- are less massive than stars
- non-luminous and spherical
- in orbit around a star
Exoplanets:
- over 600 planets confirmed to be orbiting other stars
- thousands of candidate exoplanets, observed by the Kepler Space
Telescope
Some planets have satellites (an object in orbit around a planet)
- natural satellites are also known as moons
Asteroid:
- a small, rocky object orbiting a star
Comet: - a small, icy object orbiting the sun
Galaxies: cities of the Cosmos:
- a large system of stars, dark matter, gas, and dust, all bound together by
their combined gravity
Nebulae:
- clouds of gas and/or dust
- raw materials for new stars from previous generations
Star clusters:
- Open clusters: 1000s of stars
- Globular clusters: 100000s of stars
- Our Sun probably formed in an open star cluster but has since moved out
Galaxy groups and clusters:
a group of galaxies (a few dozen up to thousands) all held together
gravitationally Many clusters form a Supercluster: Astronomy (Lecture 2) 10/22/2012 6:30:00 PM
*There are more stars in the universe than grains of sand on all of the Earth
Models in Science:
1) Scientific Model surpassed the test of nature.
2) Conceptual Model helps us think of reality. Wrestle with ideas in nature
(ex. molecule models (sticks and balls))
3) Scale Models mini versions of a larger thing.
How do the sizes of the planets compare to the distances between them?
The Astronomical Unit (AU):
- We can specify distances in the solar system by comparing them to the
average Earth-Sun distance
1 AU = 150 000 000 km = 150 000 000 000 m
- A planet twice as far from the Sun would be 2 AU away
This is known as scientific notation. For example:
Representing Large Numbers:
- The Earth is on average 150 000 000 000 m from the Sun
- In scientific notation we would write this as a coefficient between one and
ten, followed by the appropriate power of ten
- Hint: Just count the number of places the decimal would move...
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