Earth’s Role as a Body in Space Unit 1 Earth’s Role as a Body in Space 1

Welcome to Spaceship Earth!

1. The Effect of Earth’s Rotation: Say you’re just sitin’ there on Earth’s equator, all peaceful-like, minding your own business. How fast are you moving due to Earth’s rotation?

Working it Out… speed = distance / time The important point: You travel around the circumference of Earth once in 24 hours. Remember… speed = distance / time Distance … 24,888 miles (Earth’s circumference at the equator) Time… 24 hr Let’s plug in the numbers… speed =  24,888 miles / 24 hr  = 1,037 miles/hr  

Working it Out… Remember

Answer to #1 Just SITTING on the equator you are moving about 1,000 mph! You’re moving 1 mile every 3 seconds!

2. The Effect of Earth’s Revolution (Its orbit around the Sun): Now you’re standing on the North Pole. Brrrr!! Why? Well it’s a place where we can forget about the speed you’re carried due to Earth’s rotation. Up here Earth’s rotation just gently spins you around once in 24 hours on the spin axis you’re standing on. But you’re still movin’ through space because the entire Earth is zipping along in its orbit around the Sun. Assignment #2, if you choose to accept it… How fast are you moving due to Earth’s orbit around the Sun?

Hints… The important point: You travel the path of Earth’s orbit around the Sun once in 1 year. You can assume the orbit is a circle whose radius is 93,000,000 miles - the average distance between Earth and the Sun.  Circumference of Earth’s orbit around Sun… 2  x Pi x radius:  584 million miles Time it takes to orbit the Sun once… 1 year = 365.25 days = 8,766 hours = 3.16 x 10 7 seconds Speed = distance / time  =  circumference / time Speed =  584 x 106 miles/ 8,766 hrs = 66,600 miles/hr   Or: 18.5 miles/sec

Answer to #2 STANDING on spaceship Earth, you are being carried around the Sun at a speed of 18 ½ MILES PER SECOND!! Say “One Mississippi” …. There! You just moved 18 ½ miles.   That’s the same as 67,000 miles/hour.   (Maybe you should keep your seat belt on.)

3. The Effect of Earth’s Revolution Around the Center of the Milky Way Galaxy: This one is the toughest ’cause now I’ve relocated you to the north pole of … the SUN! Here you don’t experience effects 1 and 2 above. From here you can just watch the spinning Earth as it orbits you. What? Why did I put you on the NORTH POLE of the Sun? So I would not confuse you with your motion due to the Sun’s ROTATION.   (Hey, get with the program …. everything is in motion!)   Assignment #3 is to figure out how fast the Sun (carrying the entire Solar System along for the ride) is moving in its orbit around the center of the Milky Way galaxy.

Hints… The important point: You travel around the center of the Milky Way galaxy once in 240 million years. Let’s assume the orbit is a circle whose radius is 28,000 light years (Each light year is the distance that light travels in a year.) Let’s convert 28,000 light years to meaningful units of miles. One light year = 5.9 trillion miles. 28,000 light yrs x (5.9 x 1012 miles /light yr) = 1.65 x 1017 miles (That’s 165 followed by 17 zeros! That’s a loooooooooooong way across the Milky Way!)

Mind-Boggling Math Continued… Now let’s calculate the circumference of the orbit around the galactic center… Distance traveled around the Milky Way… 2  x Pi x radius: 2 x Pi x (1.65 x 1017 miles) = 1.04 x 1018 miles Time it takes to orbit the center of Milky Way once… 240 x 106 years = 8.8 x 1010 days = 2.1 x 1012 hours = 7.6 x 1015 seconds

Formulas You might need… Speed = distance / time  =  circumference / time Speed =   1.04 x 1018/ 2.1 x 1012 =  x 495,000 miles/hr Or: 140 miles/sec

Answer to #3 For you to orbit the center of the Milky Way once, in even the unfathomable time of 240 million years, still requires you to be moving very, exceedingly, incredibly, *unbelievably* fast! Right now you are cruising through the galaxy at 495,000 miles/hr! That’s 140 miles/second! Count out 17 seconds. You just moved the length of the continental United States - from New York to San Francisco! REALLY!

What?!! You’d like to travel the entire diameter of planet Earth? Wait 1 minute (actually 57 seconds). Done.

Look up in the sky! It’s a bird! It’s a plane! It’s Superman! … big deal… Just sittin’ there, [insert your name here] is WAY faster than a speeding bullet!

Welcome to Spaceship Earth!

Lesson 1 You Are Here  19

Earth’s Position in Space What is Earth’s position in the hierarchy of space? 20

I. A-1. Earth’s Position in the Universe Solar System (3rd planet from Sun)  Milky Way Galaxy (the Orion Arm)  Universe! http://www.atlasoftheuniverse.com/ 21

Earth’s Motion through Space What is the cause of Earth’s motion through space? 22

B-1.The Origin of Our Expanding Universe The Big Bang Theory The theory that the universe began as a point and has been expanding ever since The 3 yellow galaxies in each model are… Moving apart en.wikipedia.org 23

Supporters of this theory believe that all matter and radiation were compressed into an extremely small, hot, dense mass that was in existence only for a fraction of a second before rapidly expanding. Expansion has continued, but at a slower rate since then. Questions remain. Particularly, what caused it ?

Evidence for the Big Bang The observation that all other galaxies are moving away from ours at great speeds and in all directions. The cosmic microwave background radiation is thought to be evidence of this expansion. The large amount of hydrogen and helium in the universe. http://www.ugcs.caltech.edu/~yukimoon/BigBang/BigBang.htm http://science.nationalgeographic.com/science/space/universe/origins-universe-article/

A Sense of Time http://csep10. phys. utk. edu/astr161/lect/sense/sense If we were to compress the time since the Big Bang into one year, and make the time of the Big Bang January 1, The Earth was formed in mid-September. The mammals appeared on December 26. All human prehistory (from the first known stone tools) and history have occurred in the last 1/2 hour of New Year's Eve. Thus, all of human history is but a fleeting instant on the cosmic timescale.

The Universe is probably 10-20 billion years old. Our Solar System is probably 4-5 billion years old.

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B-2. The Origin of the Milky Way Astronomers hypothesize that the galaxy began as… Spherical clouds in space Newer stars have orbits … lying in the plane of the disk around the nuclear bulge http://www.google.com/imgres?imgurl=http://casswww.ucsd.edu/archive/public/tutorial/images/mw.jpg&imgrefurl=http://casswww.ucsd.edu/archive/public/tutorial/MW.html&usg=__ 29

The Milky Way http://www.atlasoftheuniverse.com/ 30

The Milky Way http://www.astropix.com/HTML/D_SUM_S/MILKYWAY.HTM 31

3. The Origin of the Solar System An interstellar cloud forms a solar system by… condensing as a result of gravity and becoming concentrated enough to form a star and possibly planets The shape and movement of a new solar system can be described as … A rotating disk with a dense concentration at the center A solar nebula is… A disk of dust and gas that can form a star 32

The Eagle Nebula http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html 33

Star formation has NEVER been observed! 34

Big Bang Theory and the END of the Universe But how will the universe END? There are several theories for this as well. http//:sciencemusuem.org.uk/educators/classroom_and_homework_rescources/universe_end.aspx