ASTRONOMY 1021 GENERAL
ASTRONONY EXAM FULL REVIEW
SUMMARY NOTES UNIVERSITY OF
WEST ONTARIO.
, lOMoAR cPSD| 19857451
Astronomy – Exam full Review
Topics:
• Scientific notation
⇨ How to write large numbers and convert (e.g. millions to thousands);
3042 (decimal needs to go 3 places to the left) = 3.042 x 10^3
0.00012 decimal goes 4 places to right= 1.2 x 10^-4
⇨ Given an incorrectly written term, be able to repair it into proper
notation: 4.01x 10^2 move decimal 2 places to right then drop 10= 401
5.7 x 10^-3 move decimal 3 places to left then drop 10= 0.0057
• Age of the universe and other important ages (in scientific notation);
13, 700,000,000 years move decimal 10 places left= 1.37x10^10, age of earth
is 4.543 billion 4,543,000,000 move decimal 9 to the left= 4.543x10^9 then
back to number move decimal 9 places to the right 4.543= 4,543,000,000
• Basic measurements: 1AU; average distance between Earth and sun about
150 million km. Technically it is the length of the semi-major axis of Earth’s orbit.
Distance to Moon; 384,000 km or 0.00256 AU. Or 1 light second.
Sun; diameter is 1.392 million km or 1,392,000 km. 8 light minutes to Earth.
Definitions:
Planet; a moderately large object that (1) orbits a star, (2) large enough for its
own gravity to make it round and (3) has cleared most other objects from its
orbital path.
Moon; an object or natural satellite that orbits a planet. The term satellite is also
used more generally to refer to any object orbiting another object.
Galaxy; a great island of stars in space, containing millions, billions or trillions of
stars. Held together by gravity, orbiting a common center.
Universe; The sum total of all matter and energy- that is all galaxies and
everything in them.
, lOMoAR cPSD| 19857451
Meteor; a small body of matter from outer space that enters the earth's
atmosphere, becoming incandescent as a result of friction and appearing as a
streak of light. Meteoroid is space meteorite landed on earth.
Comet; relatively small and ice rich object that orbits a star, can have very
sporadic orbits.
Asteroid; relatively small and rocky object that orbits a star.
Know how to write your ‘address’ in universe terms. It would go something
like this: “123 Main St., London, Ontario, Canada, Earth, Solar System, Orion
Spiral Arm, Milky Way Galaxy, Local Group, Virgo Super cluster, Universe .
• Know sizes and distances in order; order is mvemjsun, sizes are mmvenusj
acronyms for planets.
• Define AU and lightyear
⇨ Know correct definition of lightyear (a measurement of distance);
distance light travels while in a vacuum, light is constant however it can be
slowed when passed through a medium like water. Light year is 9.46
trillion km.
⇨ When looking at something that is 4 million light years away, know that it
means you’re looking at it as it was 4 million years ago.
• Cosmic Calendar
⇨ When did the earth form; Around September 3rd
⇨ When did dinosaurs pop up; December 25th
⇨ When did dinosaurs die; December 30th
⇨ When did humans appear; December 31st at 11:58
Chapter Two
Topics:
• Scale models
⇨ If the sun is a grapefruit, what is earth; a ball point 15 meters away
How far are the nearest stars (across the country); Alpha Centuri, the
distance from London to Yukon (or Calgary to St. John’s; 4000 km)
, lOMoAR cPSD| 19857451
⇨ If the earth is a basketball, how large is the moon, and where is it?; a
tennis ball 24 feet away
• The night sky
⇨ Definitions: Zenith; The highest point in the sky, directly overhead.
⇨ Altitude; the apparent height of a celestial object above the horizon,
measured as an angle.
⇨ Horizon; The boundary line dividing the ground and the sky
⇨ Meridian; The semicircle extending from the horizon due north to the
zenith to the horizon due south.
How we define the location in the sky (with altitude); We can pinpoint
the position of any object in the local sky by stating its direction along the
horizon (sometimes called azimuth) and the altitude of the object above
the horizon. Since we lack depth perception, all stars seem to be equally
distant, as if they are all glued onto a great sphere that surrounds the
Earth. This imaginary sphere is the celestial sphere.
⇨ Moon is at its highest at . What phase is it? New moon rises at
6.am remember this and you can figure out when its highest is (+6
hours that day) and when it sets (+12 hours) the next phase is the
same times for each except +3 hours for each and so on for the next
and next.
Know constellations: There are 88 constellations in the sky.
Constellations depend on latitude because your position on Earth
determines which constellations remain below the horizon. They depend
on time of year because Earth’s orbit changes the apparent location of the
Sun among the stars.
Know celestial sphere and how it works; The celestial sphere is an
imaginary sphere of gigantic radius with the earth located at its center.
The poles of the celestial sphere are aligned with the poles of the Earth.
The celestial equator lies along the celestial sphere in the same plane
that includes the Earth's equator.
The zodiac; a belt of the heavens within about 8° either side of the
ecliptic, including all apparent positions of the sun, moon, and most
familiar planets. It is divided into twelve equal divisions or signs (Aries,
Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn,
Aquarius, Pisces).