TerminologyKey words to survive an astronomy lecture

SI Measurements

• Base units• Distance: metre (m)• Mass: gram (g)• Temperature: Kelvin (K)• Time: second (s)• Current: Ampere (A)• Luminosity: candela (cd)• Substance: mole (mol)

• Derived units• Angle: radian (rad) m/m• Frequency: Hertz s-1

• Force: Newton (N) kg.m.s-2

• Energy: Joule (J) N.m or kg.m2.s-2

• Power: Watt (W) J.s-1 or kg.m2.s-3

• Modifiers• pico (p) 10-12

• nano (n) 10-9

• micro (u) 10-6

• milli (m) 10-3

• …• kilo (k) 103

• mega (M) 106

• giga (G) 109

• tera (T) 1012

Ref: http://en.wikipedia.org/wiki/International_System_of_Units

Defined Constants

• Astronomical Unit (au) 149,597,870,700 m• Parsec (pc) 3.0856776 x 1016 m

206264.81 au3.2615638 ly

Measured Constants (Pt1)

• Speed of Light (c) 299,792,485 m.s-1

• Year – Julian 365.25 days• Light-Year (ly) 9,460,730,472,580,800 m• Hubble Constant (H0) 67.80 ± 0.77 km s-1 Mpc-1

• Age of Universe 13.798 ± 0.037 Gyr 4.354 ± 0.012 x 1017 s

• Gravitational Constant (G) 6.67384x10-11 m3 kg-1 s-2

Solar System Constants (Pt2)

• Solar Luminosity 3.939x1026 W• Solar Mass 1.9818x1030 kg• Solar Radius 695,508 km

• Earth Mass 5.9722x1024 kg• Earth Radius 6,371 km• Earth Perihelion 147,098,291 km• Earth Aphelion 152,098,233 km

• Moon Mass 7.3477x1022 kg• Moon Radius 1,737.5 km• Moon Perihelion 363,104 km• Moon Aphelion 405,696 km• Moon Orbit 384,400 km• Moon Albedo 11%

Ref: http://solarsystem.nasa.gov

Distance & Angles

• Perihelion / Perigee (Closest)• Aphelion / Apogee (Farthest)• Major Axis, Minor Axis, Eccentricity

• Degrees - Minutes - Seconds (DMS)• 360o (deg) – • 60’ (arcmin) per deg – 1/21600• 60’’ (arcsec) per arcmin – 1/1296000

• Hours / Minutes / Seconds (HMS)• 24 hours (h) – 15o

• 60 minutes(m) – 1/4oor 15’• 60 seconds (s) – 1/240oor ¼’ or 15’’

Directions (Earth)

• Altitude• Azimuth• Latitude• Longitude• North, South, East, West• Equator, Tropic of Cancer, Tropic of Capricorn• Meridian• Zenith• Nadir• Pole (Celestial & Magnetic)

Directions (Space)

• Right Ascention• Declination• Sidereal Time• Horizon• Precession

Observation

• Magnitude (Absolute vs Apparent)• Luminosity• Albedo• Power• Frequency, Wavelength, Period• Red Shift / Z• Rotational Period• Orbital Period• Equinox• Solstice• Spectrum

Stellar Objects

• Star

• Main Sequence Star

• Brown Dwarf

• White Dwarf

• Neutron Star

• Cephid Variable

• Wolf-Rayet

• Pulsar

• Quasar

• Proto-Star

• Black Hole

Stellar Groups

• Binary Star• Open Cluster• Globular Cluster• Galaxy• Local Group• Large Scale Structure

Major Bodies

• Planet• Moon• Satellite• Asteroid Belt• Kuiper Belt

Minor Bodies

• Minor Planet• Comet• Asteroid• Meteor• Shooting Star• Solar System

Miscellaneous

• Constellation• Asterism• H-R Diagram

Homework

• Area of Circle • Area of Sphere

Homework (1.1)

A. For an observer located at the equator, what is the size of the Sun when observed solar noon (midday) at1) Perihelion2) Aphelion3) Mean distance

B. Repeat the above for the Moon at Lunar noon1) Perihelion2) Aphelion3) Mean distance

Homework (1.2)

A. Calculate the solar powered received by the Earth at1. Perihelion2. Aphelion3. Mean distance

B. Repeat the above for the Moon1. Perihelion2. Aphelion3. Mean distance

C. What is the maximum solar power the Earth could receive from the Moon?

Homework (1.3)

A. Calculate the force on Earth due to the Sun and express as mean value plus or minus a percentage.

B. Repeat the calculation for the Moon’s effect on the Earth.