THE UNIVERSE Trotter 2014

IV. The Sun  A. All life on Earth depends on the energy that comes from the star in the center of our solar system.  B. Energy produced by the Sun is due to hydrogen atoms fusing together to produce helium atoms.  C. The Sun is composed of 3 layers:  1. Photosphere – innermost not as hot  2. Chromosphere – transition zone  3. Corona – largest & hottest layer

V. Sun Surface Features  A. The sun appears to be a smooth layer but has many surface features including:  1. Sun spots – cooler areas  2. Prominences – arching columns of gas  3. Flares – gases shooting straight upward  4. CMEs (coronal mass ejections) – auroras All due to magnetic field & reactions across the Sun.

Solar Eclipse  Occurs when the Sun, Moon, and Earth line up  Can only happen during a New Moon  Generally, they occur every 2-5 years

Lunar Ecipse  Occurs during a Full Moon  Occurs when Moon, Earth, and Sun are directly aligned.  Next one is October 8, 2014

Auroras

Sun Cycle  Cycle lasts about every 11 years  Done so by counting sunspots  Sunspots may exist anywhere from a few days to a few months, but they eventually decay, and this releases magnetic flux in the solar photosphere

Solar Flares  The sun unleashed a powerful solar flare late Monday (Oct. 22), releasing waves of radiation into space that have already caused a short radio blackout on  Solar flares are caused when magnetic activity ramps up in certain patches, called sunspots, on the surface of our sun

I. Constellations  A. Constellations are patterns of stars that are named as a group. (88 exist in our sky)  B. All the constellations we see in the sky are part of our galaxy (large collection of stars, gas, & dust held together by gravity), the Milky Way Galaxy

II. Absolute & Apparent Magnitude  A. The actual brightness of the star refers to the stars absolute magnitude.  B. How bright the star actually is to the viewer on Earth is called the apparent magnitude  Apparent Magnitude does not equal absolute magnitutde

III. Measuring in Space  A. Distance in space is measure in light years or the distance light travels in one year (9.5 trillion km)  Used to estimate the distance of stars from Earth  The distance shifts depending on the motion/position of Earth as it orbits (parallax)

 Astronomical Unit: the distance between the Earth and the Sun  kilometers

VI. Properties of Stars  A. Basic properties of stars include:  1. Diameter  2. Mass  3. Brightness  4. Energy Output (luminosity)  5. Composition – 73% hydrogen, 25% helium  6. Surface Temperature – appears different due to very slight composition differences

VII. Classifying Stars  A. Hertzsprung & Russell Diagram shows the relationship of temperature & brightness among stars  B. Main Sequence(90%) vs. Dwarfs & Giants (bright)  Temperature: x axis  Absolute Magnitude: y axis

IIX. Life of a Star  Scientists theorize that a star goes through a few steps (as hydrogen depletes)  1. Nebula – ball of gas & dust  2. Main sequence – pieces of nebula are pulled together due to gravity, force increases energy/temperature  3. Red Giant vs. Red Super Giant – when hydrogen begins to deplete outer layer cools & expands, (if large sequence is more quick & violent)  4. White Dwarf vs. Neutron Star or Black hole – outer layers cool & escape to space leaving hot dense core

IX. Galaxies  A. Galaxies are groups into clusters.  B. Types of galaxies:  1. Spiral Galaxies  2. Elliptical Galaxies – football  3. Irregular Galaxies – small irregular

X. Gravitational Pull  A. Every 2 bodies in the universe attract each other with a force that is proportional to the product of their masses.  In other words gravitational force depends on their masses & the distance between the 2 bodies  Gravity increase with larger mass & closer proximity Think about 2 magnets