Shooting Stars• They are not stars; they are meteoroids.• The “tails” are caused by debris burning up as it enters the atmosphere.• Comets are the cause of these meteoroids and dust; when they pass near the Sun this is the result.• There are a number of meteoroid showers every year.
• The Perseids meteor shower is one of the most active meteor shower seen from Earth.• Occurs around August 12.• The showers are named after the constellation they seem to be coming from
• Certain planes fly at an altitude of 20 000 m or more.• Carry containers with a special gel used to trap the dust particles from space.• The dust is analyzed and gives us a glimpse into the mysteries of the universe
Average number Name Period of shooting stars Constellation per hourQuadrantids January 1 to 6 40 BoÖtes Lyrids April 19 to 24 15 Lyra Aquarids May 1 to 8 20 Aquarius Perseid July 25 to August 50 Perseus 18 Orionids October 16 to 27 25 Orion Leonids November 15 to 15 Leo 20 Geminids December 7 to 50 Gemini 15
The Earth in Motion Page 317 to 325• Read the Overview on page 317.• What is the Earth’s source of energy?• It’s internal core!!! We will look at this in more detail.• The Sun is also a source of energy for the Earth.• How?
• Warms the air, the water, and the ground during the day• What happens at night?• The heat dissipates!!• The changing temperature leads to:• Erosion• The water cycle• Winds• Sea currents
Continental Divide• Alfred Wegner developed this theory in 1910.• Proposed that at one time there was a supercontinent :• This was 200 million years ago (MYA)• Our continents are caused by the fragmentation of Pangaea.• His idea was not accepted until the 1960’s
• A puzzling time!!• The continents looked like they could fit together.
• Wegener there were similar rock formations in mountain chains on different continents
• Fossils were another indication that at one time the continents were close together.• The Mesosaurus is found in South Africa and Brazil!!!
• Lystrosaurus was a small land dinosaur that appears to have migrated from South America to Africa.• It could not swim• Was/is this possible?
• He proposed the idea of a single immense continent, Pangaea.• 220 MYA• The single ocean was called Panthalassa
• The supercontinent broke into large pieces that drifted to there present location.• Formed the continents and oceans we know today.• This is Continental Drift• The scientific community did not accept Wegener’s ideas!!!
You live on a plate• Read page 41• Summarize in your own words.• Pass in when complete.
The Earth’s Internal Structure• Read pages 294 and 295• What is a geologist?• Someone who studies the nature and the structure of the Earth’s crust.• They study the composition of the Earth.• Also analyze rocks, minerals, and fossils.
5 °C 1000 -1800 °C 1800 – 3700 °C 3700 – 4500 °C Above 4500 °C
• In the beginning…• The Earth was liquid• The heavy elements, iron (Fe) and nickel (Ni) combined to form the core.• The lighter elements, silicon (Si), oxygen (O)and aluminum (Al) form the mantle and crust.• When the Earth’s temperature cooled, the crust solidified.