Ch. 28 – minor bodies of the solar system

Ch. 28.1 – earth’s moon Vocabulary: Satellite - A smaller celestial body that orbits a larger body; can be artificial or natural The moon - the natural satellite of the Earth Luna - Latin for moon Lunar - pertaining to the moon

Apollo Space Program - Between 1969 and 1972, six US spacecraft landed astronauts on the moon  Moon’s gravity - only 1/6 of Earth’s because it has less mass No atmosphere - moon does not have enough gravity to hold gases Temperature - varies a lot between day and night because there is no atmosphere to absorb and transport thermal energy

The lunar surface Areas of dark and light patches on the moon Dark: impact craters filled with lava Light: highlands composed of rock Impact craters: left from impacts with other objects in space Surface is invisible from Earth without a telescope There are no volcanoes

The interior of the moon Has core, mantle and crust Density of the moon is 3/5th that of Earth. Rotation period: 27.3 days (one turn on its axis) Orbit around Earth: 27.3 days (one orbit around the Earth) Because rotation and orbit periods are the same, we always see the same side of the moon. The side we see: near side The side we don’t see: far side (only can see it from space)

The formation of the moon Giant Impact Hypothesis: 4 billion years ago, a mars-sized object struck the Earth and sent debris into orbit around the Earth. This debris eventually clumped together to form the moon. Is not a theory because of lack of data to support it.

Group activity Imagine your group is setting up a moon base. Make a list of the supplies and materials you would need to build a base for 100 people. You may wish to organize their group in a way to allow one person to be in charge of identifying resources needed to supply each major need. (10 minutes)

Light and dark side of the moon

Ch. 28.2 - Movements of the Moon The Earth Moon System The Moon has an elliptical orbit around the Earth; the distance is not always the same. average distance 384,000km (=240,000 miles)

Eclipses – when one celestial body passes through the shadow of another. Solar Eclipses When the moon is directly in between the sun and the Earth, the shadow of the moon falls on Earth’s surface Umbra – when the sunlight is completely blocked Penumbra – when the sunlight is partially blocked Can only occur during a New Moon Next solar eclipse in the US: 2017 Happens every 18 months somewhere on Earth Lasts less than 3 minutes

Lunar eclipse – when the Earth is between the sun and the moon Total lunar eclipse: moon must pass entirely into Earths umbra, otherwise it is a partial lunar eclipse Can only occur during a Full Moon Happens 1-3 times a year Lasts for several hours Moon appears reddish during a total lunar eclipse because Earth’s atmosphere filters out blue light of indirect sun light

See when the next eclipse will occur: http://www.timeanddate.com/eclipse/list.html

Phases of the moon

A. Waxing Phases of the Moon The size of the lighted side of the moon appears to increase   B. Waning Phases of the moon The lighted side appears to be decreasing Earthshine – sunlight reflected off the Earth back onto the moon. C. Time from new moon to new moon: 29.5 days

Tides on Earth Because of the gravitational pull between Earth and the moon, the Earth’s liquid is pulled toward the center of the moon, causing the tides. The sun also has an effect on the tides and when the sun and the moon are on the same side of the Earth, there are especially high tides. Sequence of high and low tides lasts 12 hrs. 25 min. Drawing of Fig 10, p. 798

Ch. 28.3 – Satellites of Other Planets Mercury and Venus have no moons Mars – 2 tiny moons Jupiter – 4 large moons Io – very hot, has volcanoes Europa – covered with a crust of ice 100 km (63 miles) thick May have ocean of liquid water below ice – scientists want to study it for signs of life Also has many small moons

Saturn – dozens of moons Titan – only moon in solar system known to have an atmosphere Uranus – 5 large and at least two dozen small moons Neptune – at least 13 moons

Ch. 28.4 – Asteroids, Comets and Meteoroids The largest minor bodies in the solar system Small, rocky irregular-shaped object that orbits the sun A dwarf planet is an asteroid that has become large enough so that gravity has caused it to become round Drawing of an asteroid: (p 805, Figure 1)

e. Location of asteroids in the solar system: In the asteroid belt located between Mars and Jupiter Inside the orbit of Mars Trojan asteroids near Jupiter Some beyond Jupiter’s orbit f. Near-Earth asteroids could be dangerous to Earth because they could inflict great damage.

Comets Small bodies made of ice, rock and cosmic dust that follow elliptical orbits around the sun. Head of the comet is made of a core (or nucleus) and a coma (spherical cloud of gas and dust)

c. Human spacecraft have taken samples of comet heads d c. Human spacecraft have taken samples of comet heads d. One tail of the comet is made of ice that has turned to gas because of heating from the sun. A second tail is made of dust. e. Most are located in the Oort cloud. f. Drawing of a comet: (p 807, Figure 3)

The Kuiper Belt A ring of icy bodies located just outside Neptune’s orbit

The Oort Cloud spherical cloud of dust and ice far beyond Neptune’s orbit; where most comets come from might be matter left over from the formation of the solar system bodies in the Oort cloud take a few million years to complete one orbit around the sun.

Meteoroids Very small bits of rock or metal Range in size from 1 mm up to 100m (33 ft). Larger than that is considered an asteroid. Meteors – Bright streak of light produced from a meteoroid burning up in the Earth’s atmosphere. Commonly called shooting stars Meteorite – Left over pieces of meteoroid that have struck Earth’s surface. Almost all meteoroids result from collisions between asteroids