Other Objects in the Solar System Scientists find valuable information about the origin and evolution of our universe from examining other objects in our Solar System. Copy down the purple sections. Planetary Moons Satellites or Moons – large natural objects that revolve around planets moons contain huge amounts of useful minerals that humans may mine one day

Some Moon Facts Average distance from Earth: 384 000 km. Due to the elliptical nature of the orbit - - Minimum distance: 363 000 km (called perigee) - Maximum distance: 405 000 km (called apogee). Diameter: 3 500 km (1/4 that of Earth's) However as viewed from Earth, the size of the Moon appears to change by as much as 11% from perigee and apogee. Orbital path: elliptical but constantly slightly altered In addition to the Earth's gravity, the Sun is also exerting a gravitational force on the Moon as well. The Sun's gravity sometimes causes the Moon to speed up or slow down slightly in its orbit. Rotation: it takes 27.3 days to turn once on its axis (this is why we always see the same face of the moon) Surface: filled with hills and valleys as well as craters caused by the impact of large and small objects from space

Moon & Tides (4:00 min): http://www.youtube.com/watch?v=rRPtNAA-9UE Cookie, onion, orange analogy (2:00 min): http://www.youtube.com/watch?v=CTQ6ciHENgI&NR=1

Recall: Phases of the Moon

Asteroids Asteroids – made up of stoney/rocky and “metallic” materials (eg. iron) rich in minerals (like planetary moons) largest asteroid is only about 100 km in diameter about 91 Apollo asteroids have been identified – potential for colliding with Earth (theory for extinction of the dinosaurs) called minor planets or planetoids rocky leftover mass of the inner planets

Asteroid belt – between Mars and Jupiter there is a ring of asteroids Scientists think it might have formed into a planet if the gravitational force of Jupiter weren’t so strong

Meteors and Meteorites Meteoroid – lump of rock or metal that travel throughout the solar system with no fixed path similar in origin to asteroids and comets when trapped by Earth’s gravity it is pulled through the Earth’s atmosphere This causes the meteoroid to heat up and vapourize due to the friction with the molecules in the atmosphere which results in a… Meteor incorrectly called“shooting star” bright streak of light across the sky, occurs in seconds Most of the meteoroids are completely burned up in our atmosphere, however, a few very large ones will get through and are then called…

Meteorites - if a meteor does not burn up completely and strikes the Earth’s surface - produces craters when they hit the ground Example: Barringer Crater, Winslow, Arizona, at 1.2 km in diameter, smaller crater

Other craters: This incredible 72km wide impact crater in Quebec has slowly transformed into its current state. What was originally the rim of the crater has since eroded away due to glaciation. The impact occured around 212 million years ago and the diameter of the meteorite is estimated to have been approximately 5km. With an astounding diameter of around 300km, Vredefort basin in south Africa is currently the largest confirmed impact crater on Earth and also one of the oldest at 2 billion years. the crater was the result of an extreme impact with an object whose diameter was 10km.

How Much Damage?

What causes meteor showers? Lots of falling stars Clouds Debris left in the path of a comet Solar wind particles

Meteoroid Shower Meteoroid shower often occurs when the Earth cross the orbit of comets. The many particles left by the dust tail of the comets ‘collide’ with the Earth, causing the meteoroid shower.

The Cause of Meteor Showers P55/Tempel-Tuttle

The 1833 storm

The 1966 storm

1997 Leonids from Orbit Meteor shower associated with the comet Tempel-Tuttle. The Leonids get their name from the location of their radiant in the constellation Leo: the meteors appear to radiate from that point in the sky.

Comets Comets – chunk of frozen matter that travels in a very long orbit around the sun basically a “dirty snowball” (ice, dust and gas) with an elliptical orbit around the sun icy leftovers of the outer solar system as it approaches the sun, it is warmed and the frozen substances become gas creating a gaseous head and long tail Example: Halley’s Comet – returns every 76 years

The most distant region of the solar system is the Oort Cloud. - It consists of billions of fragments of ice and dust, and is thus a major source of comets.

Comets The strong gravity of the Outer Planets sucked in most of the comets in between Jupiter and Neptune, either sending them to a collision course with other planets, or ejecting them to the Kuiper Belt and the Oort Cloud. Comets beyond the orbit of Neptune have time to grow bigger and stay in stable orbit. Pluto may be (the biggest) one of them.

Comet Tails Comets develop tails only when the get close enough to the Sun. Comet tails always point away from the Sun—This is how scientists first realized the existence of solar wind.

Composition of Comet Tails Plasma tail consists of gas escaping from the coma. The gas are ionized by solar UV radiation. Since they are charged particles, solar wind carries them outward from the Sun. The plasma tails always point away from the Sun. Dust tail consists of dust-sized particles from the coma. They are pushed by the radiation pressure (sun light), and generally curve back to the direction where they came from.

Hyakutake

Hale-Bopp

Comet Halley 1910 Orbit Link Comet Halley was visible in 1910 and again in 1986. Its next passage will be in early 2062. The period of its orbit is every 76 years. The average period of Halley's orbit is 76 years but you cannot calculate the dates of its reappearances by simply subtracting multiples of 76 years from 1986. The gravitational pull of the major planets alters the orbital period from revolution to revolution.

Two Showers for Halley due to The Orionid meteor shower is one of two showers that occur annually when Earth passes through Halley's Comet dust and debris. http://www.suite101.com/content/the-orionid-meteor-shower-is-debris-from-halleys-comet-a280661#ixzz1AukiHym8

Home work: Finish Glossary handout. Start to Review for Astronomy Quest!