lecture12 - Astronomy Picture of the Day Saturn as viewed...

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Astronomy Picture of the Day Saturn as viewed by Cassini Announcements Quiz grades posted on EEE Quiz average 6.4/10, median 7/10 Midterm exam next friday Same format as the quiz Bring a scantron form #288 and a pencil I will post a seating chart on the class web site: you must look at this in advance so you'll know where to sit! The Terrestrial Planets The Terrestrial Planets Distance from Sun (A.U.) Mercury Venus Earth Mars 0.39 0.72 1.0 1.52 The Terrestrial Planets Orbital Period (years) Mercury Venus Earth Mars 0.24 0.62 1.0 1.88 The Terrestrial Planets Radius (Earth radii) Mercury Venus Earth Mars 0.38 0.95 1.0 0.53 Earth's equatorial radius is 6378 km The Terrestrial Planets Mass (Earth masses) Mercury Venus Earth Mars 0.055 0.81 1.0 0.11 Note: our Moon has a mass of about 0.012 Earth masses The Terrestrial Planets Mean Density (g/cm3) Mercury Venus Earth Mars 5.43 5.24 5.51 3.94 The Terrestrial Planets Rotation Period (days) Mercury Venus Earth Mars 59 243 1.0 1.03 The Terrestrial Planets Axis Tilt (degrees) Mercury Venus Earth Mars 0.0 177 23.5 25.2 The Terrestrial Planets Number of Moons Mercury Venus Earth Mars 0 0 1 2 (both very small) The Terrestrial Planets: key properties Close to the sun Short orbital periods Earth is the largest and most massive terrestrial planet High densities: metallic/rocky composition Few if any moons Terrestrial planet atmospheres Atmospheric composition, in percent Gas CO2 Nitrogen Oxygen Argon Neon Earth 0.03 78.1 21.0 0.93 0.002 Venus 96 3.5 0.003 0.006 0.001 Mars 95.3 2.7 0.15 1.6 0.0003 Terrestrial planet atmospheres Atmospheric composition, in percent Gas CO2 Nitrogen Oxygen Argon Neon Earth 0.03 78.1 21.0 0.93 0.002 Venus 96 3.5 0.003 0.006 0.001 Mars 95.3 2.7 0.15 1.6 0.0003 The Earth The Earth's Structure Inner core: solid iron Outer core: molten iron Mantle: mostly solid but somewhat viscous, mix of silicon dioxide, magnesium oxide, iron oxide, other compounds Crust: solid outer layer, mainly basalt and granite Terrestrial planet interiors Early in their history, the planets were fully molten Differentiation: the process by which denser materials sink toward the center, creating a layered structure The earth's crust Major processes that shape the earth's surface: Plate tectonics (continental drift) Volcanic activity Impact cratering (important in the earth's early history, but not happening very frequently now) Erosion- wearing down of mountains and other features The structure of the earth's surface is constantly changing because of these processes! Continental Drift Continents of the future Plate tectonic maps and Continental drift animations by C. R. Scotese, PALEOMAP Project (www.scotese.com) Continents of the future Continents of the future Continents of the future Tectonic Plates Hot-spots and Volcanic Activity Volcanism Olympus Mons volcano on Mars Eruption on Jupiter's moon Io Impact Cratering Earth Mars The moon Erosion Eroded stream channels on Mars Stream channels on Saturn's moon Titan, possibly from methane rain Tides High and low tides at the Bay of Fundy in Canada The Tides Tides are the result of the differential gravitational pull of the moon on different parts of the earth stronger pull on this side weaker pull on this side Gm1 m2 F = 2 d The moon's gravitational pull is stronger on the side of the earth closest to the moon, and weaker on the opposite side The Tides N the moon's average gravitational pull on the earth S The Tides N stronger pull on this side weaker pull on this side average pull on center S (note: these diagrams are not drawn to scale!) The Tides If we subtract off the average gravitatonal force felt by the earth, we are left with the differential gravitational pull at each point on the earth's surface N S The differential gravitational pull on different parts of the earth, relative to the average gravitational pull, is responsible for the tides The Tides The oceans can flow in response to these tidal forces N S The Tides Because of the earth's rotation, there are 2 high and 2 low tides each day (almost) moon's orbit this way N Top view, looking down on the earth's north pole Because of the moon's orbital motion around the earth, the time between two successive high tides is 12.5 hours N N The Tides The moon's orbit is at an angle to the earth's equator N S So, for an observer at a given location on earth, the two high tides in a given day won't have equal height The Tides The sun also exerts a tidal force on the earth and affects the ocean tides But, the tides due to the sun are only 1/2 the strength of the tides due to the moon The Tides The earth's diameter is 3.3% of the earth-moon distance but only about 0.0085% of the earth-sun distance The Tides "Spring tides": the highest tides occur when the earth, moon, and sun are well aligned "Neap tides": high tides are less high when the earth, moon, and sun form a right angle The Tides "Spring tides": the highest tides occur when the earth, moon, and sun are well aligned "Neap tides": high tides are less high when the earth, moon, and sun form a right angle ...
View Full Document

Page1 / 42

lecture12 - Astronomy Picture of the Day Saturn as viewed...

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online