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Earth & Space Science Part 1: Stargazing. 1.1 Measuring the Universe. Making Unmanageably BIG Numbers Manageable. Two Methods: Scientific Notation (Speed of Light = 300,000,000 m/s = 3.0 x 10 8 m/s) Bigger Units (Speed of Light = 300,000,000 m/s = 300 Mm/s). 1. Scientific Notation.
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Earth & Space SciencePart 1: Stargazing 1.1 Measuring the Universe
Making Unmanageably BIG Numbers Manageable Two Methods: • Scientific Notation (Speed of Light = 300,000,000 m/s = 3.0 x 108m/s) • Bigger Units (Speed of Light = 300,000,000 m/s = 300 Mm/s)
1. Scientific Notation General Form: x 10 Exponent = # of places to move decimal Number between 1 and 10
Examples of Scientific Notation World Population: 6,600,000,000 = 6.6 x 109 US Population: 301,000,000 = 3.01 x 108 Illinois Population: 1.28 x 107 = 12,800,000 Bloomington Population: 7.097 x 104 = 70,970
A Video of Scientific Notation Awaits you here….
Moon Earth Jupiter Sun Asteroid Galaxy Your Mamma Who’s biggest? Rank the following items in order of INCREASING size (smallest → biggest):
2. Bigger Units Metric Prefixes: Kilo- = 1,000 Downs → Wrigley Field = 230,000 m = 230 km Mega- = 1,000,000 Downs → Moon = 384,000,000 m = 384 Mm Giga- = 1,000,000,000 Downs → Sun = 150,000,000,000 m = 150 Gm
Astronomical Unit (AU) • Distance from Earth to Sun. • Useful for measuring distances within solar system. 1 AU = 1.5 x 1011 m = 93 million miles Sun → Earth = 1 AU Sun → Mars = 1.52 AU Sun → Jupiter = 5 AU
Light year (ly) • Distance light travels in 1 year. • Useful for measuring distances between stars. 1 ly = 9.5 x 1015 m = 63,200 AU = 5.9 trillion miles Downs → Alpha Centauri = 4.4 ly
A Comparison of Distance Units(Not even close to scale) Meter. Use for objects and diameters of planets, moons, stars, etc. Astronomical Unit. Use for distances inside solar system Light Year. Use for distances between stars
Review The distance to the moon is 384,000,000 m. • What is this in scientific notation? 3.84 × 108 m • How many kilometers is this? 384,000 km
More Review What unit would you use to measure the distance from Earth to the planet Saturn? a) Astronomical Unit b) light year What unit would you use to measure the distance to Betelgeuse, a star in the constellation Orion? a) Astronomical Unit b) light year
Mass vs. Weight Mass – Amount of “stuff” in an object An object’s mass is the same anywhere in the universe. Weight– How strongly gravity pulls on an object An object’s weight varies from planet to planet
More Mass vs. Weight On Earth: Mass of moose = 720 kg Weight of moose = 1200 pounds On Moon: Mass of moose = 720 kg Weight of moose = 200 pounds
Units of Mass • Kilogram (kg) 1 kg = 2.2 pounds Example: Mass of an astronaut is 90 kg. An Official Kilogram ~ 1 ½ “ x 1 1/2 “ cylinder of platinum and iridium
Earth Another Unit of Mass Earth Mass 1 Earth mass = 6.0 x 1024 kg Useful for measuring masses of planets Example: Mass of Jupiter is 318 Earth Masses
Sun And Another Unit of Mass Solar Mass 1 Solar mass = 2 x 1030 kg = 330,000 Earth Masses Useful for measuring masses of stars Example: Mass of Betelgeuse is 14 Solar Masses
Measuring Apparent Magnitude, m (aka – “Brightness”) Hipparchus (Greece, ~200 BC) • Ranked stars on 6-point scale • 1st Magnitude: 20 brightest stars • 2nd Magnitude: Next brightest etc…. • 6th Magnitude: Faintest stars visible with naked eye Similar method used today!
Today’s Apparent Magnitude Scale • Decimals and numbers outside of 1-6 range OK • Each increase of 1 in magnitude is an increase of 2.5x in brightness • Add scale! Examples:
What affects brightness? • Distance from us • Size of star • Temperature of star
3 Scales to Use • Fahrenheit • Celsius • Kelvin
Examples of Temperatures Average Earth Temperature: 58.3o F = 14.4o C = 287.4 K Surface of Sun: 10,800o F = 6000o C = 6270 K Core of Sun: 27 million o F = 15 million o C = 15 million K Outer Space -454o F = -270.3o C = 2.7 K