Transcript Minor Bodies of the Solar System

Minor Bodies of the Solar System
Moons, Asteroids, Comets, Meteoroids
Chapter 28
Satellite: A body that
orbits another body
(can be natural or
artificial)
-6 planets have smaller
bodies that orbit them
These natural satellites
are called moons
Our Moon
• Moon has 3 layers
– Crust
• Covered in dark spots called mare
(MAHR ay)
• Many craters: bowl shaped
depressions from debris impact
• Regolith: layer of dust and rock
• Lunar rocks- similar to rocks on
earth
• One side always faces away from
earth (near-side, far-side)
– Pull of earths gravity makes farside thicker
Our Moon
• Mantle
– Rock that is rich in
silica, magnesium,
and iron
• Core
– Small, made of iron
• Neither completely
solid nor completely
liquid
Formation of the Moon
• Giant Impact Hypothesis
– Mars sized body struck earth
• Collision ejected chunks of earths mantle into orbit
around earth to form Moon
https://www.youtube.com/watch?v=dw_Y_gujBwU
Meteorite Bombardment
• As Moon cooled it
was struck with
debris from
formation of solar
system
– This produced
craters and regolith
Phases of the Moon
Phases of the Moon
Movement of the moon
• Moon orbits earth in an ellipse
– Closest to Earth at Perigee
– Furthest from Earth at Apogee
• Average distance from Earth is 384,000 km
• Moons orbital period is 27.3 days (new moon
to new moon)
• Moons rotation is same as period
• We always see same side of moon
Eclipses
Eclipse: Where one celestial body passes
through the shadow of another.
– Solar Eclipse: When moon is directly between the
sun and the earth. Shadow of moon is on earth
Umbra-directly in line
(total eclipse)
Prenumbra- not
directly in line,
surrounds umbra
(partial eclipse)
Eclipses
• Lunar Eclipse: When earth is between the
moon and the sun. Shadow of Earth is on
moon
Moon and Tides
• Tidal Bulges from Moon’s gravitational pull on
earth
– Regular rhythm because of earths rotation
Asteroids
Fragments of rock that orbit the sun
• Sometimes called minor planets or planetoids.
• Small rocky bodies floating between Mars and Jupiter
• Possible extra planet that didn’t totally form
Four types of orbits:
• asteroid belt
• Apollo asteroids(cross Earth’s orbit)  close
encounters!
• Amor asteroids (cross Mar’s orbit)
• Trojan asteroids (inside the orbit of Jupiter).
Comets
A small body of ice, rock, and cosmic
dust that follow highly elliptical
orbits around the sun
• Has a core and a tail
• Halley’s Comet passes earth every
76 years. Last in 1986. Next in 2061
• Hale-Bopp passes every 5-10 years.
Hale-Bopp 1997
Meteoroids
• Less than 200-300 km in diameter
• Most are less that 1mm
• Chunks of rock & iron smaller than asteroids
orbiting the Sun.
• Sizes range from grains to 100 meters across.
Meteor: Streak of light when a meteoroid enters
the Earth's atmosphere and burns up. Most
are tiny grains.
Meteorite: Any remnant that reaches the
ground intact.
Results of Tunguska Blast, Russia
Meteor Crater, AZ