Do-NOW 9/23 PLEASE COLLECT YOUR INBS FROM THE BOTTOM SHELF! INB Check #1 12 Current Event #1 13-14 Ch 3.1: The Universe, Solar System, and Earth (notes) 15 Pg 3-9 #1-14 16 WOD: BEDLAM (BED lum) n. a place or scene of noisy uproar and confusion During Brain Breaks, there is total bedlam in the classroom. PLEASE COLLECT YOUR INBS FROM THE BOTTOM SHELF! Yellow half sheet goes under DO-NOW on page 12

The Universe, Solar System, and Earth Chapter 3.1 The Universe, Solar System, and Earth

We Are Not Alone Where did Earth, the solar system, and the stars come from? Where did life come from? When we ask these questions, we are really asking where did we come from.

Origin of the Universe Astrology- study of the supposed influence of the stars and planets on human affairs Not considered a science in the modern sense Astronomy- the scientific study of the universe, especially of the motions, positions, sizes, composition and behavior of celestial objects

Origin of the universe Our universe began as a concentrated single point, containing all known matter and energy. Approximately 3.7 billion years ago this single point began to expand – an event known as the Big Bang. The universe has been expanding ever since.

Origin of the universe Matter is not distributed uniformly throughout the universe. A natural property of matter, gravity, began attracting helium and hydrogen atoms together. As the density increased, matter collapsed and compacted under its own weight, causing a warm, dense core called a protostar.

Origin of the universe The theorized “life cycle” of a star: The nuclear fusion reaction from protostars creates stars. The star burns for millions of years, consuming it’s hydrogen. Heavy elements form as hydrogen atoms fuse during the “life-cycle” of a star. The core becomes denser and eventually collapses under the extreme gravity forces generated by the density. The star may explode causing a supernova. Supernova explosions account for the distribution of heavy elements throughout the universe. http://www.youtube.com/watch?v=PM9CQDlQI0A

Origin of the solar system The sun, Earth, and other planets in the solar system are only one of the millions of such systems that make up the Milky Way Galaxy. The current theory of how our solar system formed, with the planets orbiting the sun, began with a large cloud of hydrogen and helium called a nebula. A shock wave from a supernova caused the cloud to condense, which caused it to spin. As the cloud collapsed and became denser, it flattened in a disk due to the rotation. At the center a protostar developed and began the nuclear fusion process, becoming the sun.

Origin of the solar system Some gas continued to revolve around the sun, eventually condensing into masses too small to become stars – they became the planets. This theory that the solar system originated as a nebula is called the nebular theory.

Origin of earth According to nebular theory, Earth (and other solar system planets) formed through accretion. Accretion is the process by which small particles clump together because of gravity. As a mass grows the more gravity it has, the more additional mass it attracts. The Earth’s growing mass caused its core to compress causing the core to heat and become molten liquid. The outer core is still molten. With this molten liquid, heavy matter, iron and nickel, sank toward the center, while light matter, oxygen and silicon, moved toward the surface. This process of density stratification formed the layers of the Earth http://www.youtube.com/watch?v=Tz8ithgTBj4

Origin of the moon The most widely accepted theory for the moon’s origin is the Orpheus theory. Orpheus theory says that a planet-sized body struck Earth during its early development and sent some of its material into orbit, forming the moon.

Origin of the atmosphere and oceans When the Earth cooled enough for the surface to form a crust, gases from volcanic activity escaped accumulating as an early atmosphere. The surface was still so hot that when water vapor formed clouds, then rain, the rain boiled off again when it hit the ground. Finally, the Earth cooled enough to allow the rainwater to accumulate and the oceans formed as water vapor condensed.

Origin of the atmosphere and oceans The process that allowed life to form began with development of the oceans. Carbon dioxide dissolved into young oceans, leaving a nitrogen-rich atmosphere. Scientists think these were the conditions required for life. Ozone, an oxygen molecule found high in the atmosphere, is also important because it protects life from ultraviolet radiation.

Origin of the atmosphere and oceans There was no oxygen in the early atmosphere as it was not needed. Oxygen, essential to life today, entered the atmosphere about 1.5 billion years ago when photosynthesizing organisms began using carbon dioxide and releasing oxygen.

Homework 9/23 Page 3-9 #1-14 You must write the full question with correct answer Question + letter answer = half points Letter answer only = no points