Astronomy Part 2 Earth in the Universe Motions

Astronomy Part 2 Earth in the Universe Motions of Earth, Moon, and Sun

Earth in the Universe

Eccentricity and Ellipse An ellipse is an oval shape. n Earth’s orbit around the sun is an ellipse. n Within an ellipse, there are two fixed points called foci. n In our solar system, the sun is ALWAYS ONE of those foci. n

An ellipse is an example of a “conic section”. Circles and hyperbolas are others. All are possible forms for orbits. You can make an ellipse with 2 tacks and a string. The tacks are the “foci”, and if you put them further apart, the ellipse is more “eccentric” (one tack makes a circle).

Eccentricity and Ellipses n The degree of flatness or “ovalness” of an ellipse is measured by eccentricity. n This formula is on page 1 of your ESRT!

Pg 1 ESRT

Eccentricity and Ellipse n The more oval the orbit is, the more eccentric it is, or the higher the eccentricity. Increasing Eccentricity

Eccentricity and Ellipse n Calculating Eccentricity: Major Axis X Foci 1 X Foci 2

Eccentricity and Ellipse Calculating Eccentricity: n When you measure those 2 distances and calculate them, you will NEVER get higher than 1!! n The closer to 1 you are the MORE oval or eccentric the orbit. n The closer to 0 you are the LESS oval or eccentric the orbit. n

Gravitational Force n n n The closer 2 objects are to each other, the greater the gravitational pull between them. Therefore, during the perihelion – when Earth is closer to the sun, there is a greater gravitational pull between it and the sun. This makes the Earth speed up a bit in its orbit around the sun during that time.

Gravitational Force Perihelion Aphelion

Page 15 in ESRT – Turn there now!

The Big Bang Theory The universe started with a concentrated area of matter and energy. n 15 -20 billion years ago. n Then, it exploded and has been expanding ever since. n Faster moving stuff traveled farther. n

The Big Bang Theory n Matter began to clump together forming stars and galaxies. n The universe continued to expand is still expanding today.

The Big Bang Theory What proof do we have that the big bang did happen? n 1. Recently, scientists have found long -wave radiation coming from all directions in the universe. This is the energy that was created from the Big Bang. n 2. The universe is still expanding. n

Universe Expansion How do we know the universe is expanding? n Pg. 14 in the ESRT shows the electromagnetic spectrum. n Notice that in the visible spectrum there all the colors of the rainbow. n

Pg. 14 ESRT Shortwave Longwave

Universe Expansion n n When looking at the visible spectrum wavelengths are shifted either to the blue end (shorter wave) or the red end (longer wave). This shift in wavelengths is called the Doppler Effect. If they are shifted towards red, they are moving away from you. If they are shifted toward blue, they are coming towards you.

Universe Expansion n When scientists look at the universe, they see a red shift. This proves it is moving away from us, thus, expanding!

Red Shift Light from galaxies moving away Notice the shift to the red end

Blue Shift Light from galaxies moving toward us Notice the shift to the blue end

Galaxies The basic unit of matter in the universe is a galaxy. n A galaxy is a collection of billions of stars and gas and dust. n Our solar system is part of the Milky Way Galaxy. n The Milky Way is a spiral-shaped galaxy. n

Stars A star is usually a large ball of gas held together by gravity. n Produce tremendous amounts of energy and they shine. n Energy is produced by nuclear fusion – combination of nuclei of smaller elements to form nuclei of larger elements. n

Stars have different: n Size n Composition n Temperature n Color n Mass n Brightness n

Stars SIZE – 5 main categories: n 1. Medium sized n 2. Giants n 3. Supergiants (Largest) n 4. White Dwarfs n 5. Neutron Stars (smallest) n

Stars COMPOSITION n Mostly made up of hydrogen (60 -80%) n Most of the rest is helium. n About 1% of other elements. n Determined by looking at the color of the star. n

Stars n n n TEMPERATURE Color also indicates temperature hottest surface 50, 000 °C coolest -3000°C Blue are hottest stars. Red are coolest stars. Blue White Yellow 35, 000 °C 10, 000 °C 6, 000 °C Red. Orange 5, 000 °C Red 3, 000 ºC

Stars BRIGHTNESS n A measure of a stars brightness is its magnitude. n Apparent magnitude is how bright it looks from Earth. n Absolute magnitude is how bright it really is. n

Stars Hertzsprung-Russell Diagram: n Found that as temperature increased, so did absolute magnitude. n 90% of stars followed this pattern n Called main sequence stars n Other 10% were once main sequence stars but have changed over time. n

Absolute Magnitude Supergiants Ma in s Giants equ enc e Wh 50000 20000 ite D war 10000 fs 6600 6000 5000 3000

STAR EVOLUTION

The good news!! This is all for free on pg. 15 of the ESRT!

Our Solar System n n The solar system is the sun and all objects that orbit the sun under its gravitational influence. Our solar system has 1 sun and 8 planets.

Our Solar System n The Sun n An average star – Main Sequence n Over 1 million Earth’s would fit inside. n 1/4 the density of the Earth. n Made of 4 layers.

Putting things into perspective…

Putting things into perspective…

Putting things into perspective…

Putting things into perspective…

Putting things into perspective…

Solar Prominence

Remember - a lot of information about our solar system is free of charge on page 15 of your ESRT!!!

Motions of Earth, Sun, and Moon

Models of Apparent Motion Remember, apparent motions of celestial objects mean these objects appear to move, but really, it’s Earth that is moving. n There have been 2 main models to explain these apparent motions. n 1. Geocentric Model n 2. Heliocentric Model n

Models of Apparent Motion n n Geocentric Model: Early cultures believed this one. It says the Earth is the center of everything and all objects move around it. Geo = Earth

Models of Apparent Motion Heliocentric Model: n Model that is used and believed today. n It says the sun is the center of our solar system and everything moves around it. n Helio = sun n

Earth’s Motions n n n We know that the Earth rotates. However, HOW do we know this for sure? 1. The Focault Pendulum The path of the pendulum changes in a predictable way throughout the day. 2. The Coriolis Effect All particles on Earth, including wind, are deflected or curved from their original path.

The Motions of the Moon n n Revolution – Counter clockwise, 1 revolution takes 27 1/3 days. Rotation - Counter clockwise, 1 rotation takes 27 1/3 days. Always see the same side of the moon. Phases of Moon- 29½ days long.

The Motions of the Moon Why are there an extra 2 1/6 days? n Moon has to revolve for 2 more days to get back to the new moon phase. n This occurs because the Earth is revolving around the Sun. n

Phases of the Moon n n Caused by the positions of the Earth, Moon, and sun. They repeat because the moon orbits the Earth.

Phases of the Moon n n n n New Moon Waxing Crescent First Quarter Waxing Gibbous Full Moon Waning Gibbous Last Quarter Waning Crescent Moon Phase Calculator

New Moon Waxing Cresent

First Quarter Waxing Gibbous

Full Moon Waning Gibbous

Last Quarter Waning Cresent

Eclipses n n n 2 types of eclipses: 1. Lunar eclipse – eclipse of the moon. Earth casts a shadow on the moon during the FULL MOON phase.

Penumbra Umbra

Eclipses 2. Solar Eclipse: n Can only happen during a NEW MOON phase. n In rare cases the moon in this phase can block out the sun, casting a shadow onto Earth, which causes a solar eclipse. n

Partial Solar Eclipse Total Solar Eclipse

NASA Eclipse Web Page

Tides

Tides n n The gravitation between the Earth, Moon, and Sun results in a cyclic rise and fall of ocean waters on Earth. These are called tides. A bulge of water is a high tide and occurs when the gravitational pull of the moon is the greatest. This will occur on the side facing the moon, and on the exact opposite side.

Tides n n On the other 2 sides, there will be a low tide. This is where the gravitational pull of the moon is the least.

Tides n n Spring Tide – every new and full moon phase the Sun, Earth, and Moon are in a strait line. This causes even higher high tides. Neap Tide – During the first and third quarter moon phases, the Sun, Earth, and Moon are at a right angle to each other. This causes even lower low tides.