Atmosphere : Consisting mostly of Nitrogen (78%) and oxygen (21%).
Earth’s oxygen atmosphere was likely created by plants early in earth history
Continental Drift : The continents may have once been connected together in a single landmass named Pangaea.
Plate Tectonics : The earth’s outer crust is broken into about a dozen plates
These plates move slowly, growing in some areas and sinking back into the earth
Edges of plates feature earthquakes, volcanoes, and mountains
The continents shift and move slowly over time.
At one point, the continents are believed to have been together, in the form of a supercontinent called Pangaea.
This supercontinent then separated into smaller continental plates.
Some plates separated further, creating mid-oceanic ridges, while others collided, creating large mountain ranges.
Eventually the familiar continents of today emerged.
The Earth’s Major Tectonic Plates The boundaries of Earth’s tectonic plates show different motions Sliding past one another Separating Colliding
Earth’s magnetic field is strong
The field protects life from excess solar radiation
Interaction between the earth’s magnetic field, atmosphere, and solar radiation (solar wind) create the northern lights
Earth is surrounded by a magnetic field believed to be produced by convection in its molten iron core. The magnetic field produced is similar to that of a bar magnet. The axis of the Earth’s magnetic field differs from the axis of rotation by 11 °, placing the north magnetic pole in a different location than the geographic (true) North Pole.
The Earth’s Magnetic Field Protects us from the Solar Wind
Near the magnetic poles, these particles sometimes leak into our atmosphere, causing the gases to glow. This is known as the aurora or northern lights.
Earth’s Moon : Of the four inner planets, earth alone features a large satellite
The moon likely formed early in earth history when our planet was struck by a Mars-sized object
This impact ejected material to form the moon
Life : Earth is the only place in the universe where life is known to exist.
Life may have existed once on Mars (this is still unproven)
Organic molecules (e.g., amino acids) exist in comets and meteorites
It is likely that the components of life came from space, perhaps from meteorites or comets
Moon Data http://www.vegaattractions.com/astrology/symbols.html www.solarviews.com/cap/ moon /v moon 1.htm
Surface Gravity if Earth = 1
Mass if Earth = 1
Length of “Day”
29.5 earth days
Diameter if Earth = 1
Length of “Year” (revolution around the earth)
29.5 earth days
Diameter at the Equator
Mean Distance from Earth 238,900 miles
Earth to Moon : About 250,000 miles
Roughly the distance between New York City and Los Angeles.
The moon is the second brightest object in the sky after the sun.
The moon is actually made of dark material, its albedo is 11%
Lunar phases result from the moon’s revolution around the earth
Animation: The Moon’s Rotation
Animation 6.5: The Moon’s Rotation
Synchronous: The moon rotates on its axis and revolves around the earth in 29.5 days
Apogee, closest to earth
Perigee, farthest from earth
Due to its synchronous rotation and revolution, the moon always presents the same face towards the earth
The back side of the moon was first imaged by a Russian robotic space mission in 1959 (Luna 3)
Perigee and Apogee Apogee and perigee cause the moon to be slightly larger or smaller throughout the year
The moon appears to “rock” and “nod” due to its elliptical orbit and tilt compared to earth
As a result, 56% of the moon’s surface is visible from earth
The maria make up the shape of the “man in the moon” or the “rabbit in the moon.”
Latin for “sea”.
Apollo 11 landed at Mare Tranquilitatis, the “Sea of Tranquility”
Originally immense impact basins, later filled with molten lava
Lunar Maria (Seas) Sea of Clouds Mare Nubium Sea of Moisture Mare Humorum Known Sea Mare Cognitum Sea of Isles Mare Insularum Ocean of Storms Oceanus Procellarum Sea of Rains Mare Imbrium Sea of Cold Mare Frigoris Sea of Vapors Mare Vaporum Sea of Nectar Mare Nectaris Sea of Tranquility Mare Tranquilitatis Sea of Serenity Mare Serenitatis Sea of Fertility Mare Fecunditatis Sea of Crises Mare Crisium Meaning Name
Thousands of craters
Most result of meteorite impacts
Up to 100 miles in diameter
Can exhibit central mountains and bright streaks of ejecta
Galileo was the first scientist to observe lunar craters with a telescope (1609)
Formation of the Moon : There are four major theories :
Co-Accretion : The earth and moon formed individually and at the same time from the solar nebula
Fission : The moon split off from the earth
Capture : The moon formed elsewhere and was later captured by the earth
Impact : The earth collided with a Mars-sized body (not the planet Mars!) and the moon formed from the ejected material. This theory is now widely accepted.
The similarity in materials making up the Earth and Moon suggest that the Moon may have been created from Earth material ejected after a collision with a large planetesimal. EARTH MOON This computer simulation shows how the Moon could have been formed in a collision between the Earth and a large planetesimal.