# Really, just how important and significant are you…………?

## Presentation on theme: "Really, just how important and significant are you…………?"— Presentation transcript:

Really, just how important and significant are you…………?

Cosmology The study of the contents, structure, and evolution of the universe from the beginning of time……to the future.

Was Monty Python right? “that’s orbiting at 19 miles a second” Calculate if this is in any way an accurate figure? What data do you need to do this? Earth – Sun distance = 9.29x10 7 Miles Year = 365.25 days

Calculation Orbit Radius = 9.29x10 7 miles Orbit Radius = 9.29x10 7 miles Circumference= distance travelled= 2πR Circumference= distance travelled= 2πR = 2 x π x 9.29x10 7 = 583707915 miles Speed = Distance ÷ Time (Time =365.25 days) Speed = Distance ÷ Time (Time =365.25 days) Speed = 1598105 miles/day Speed = 1598105 miles/day or 18.5 miles per second…Pretty close!!!

Our Solar System Lets start closer to home…. Lets start closer to home…. watch the video “Our Solar Sytem” and make notes.

Cosmology Projects/Presentations The Earth, Moon and Sun The Earth, Moon and Sun The Moon The Moon The Solar System The Solar System Stars & Constellations Stars & Constellations Each group will also have to explain one topic from Cosmology Mathematics.

The Earth, Moon & Sun Night & Day Night & Day Seasons Seasons Solar Eclipses Solar Eclipses Solar Flares Solar Flares Aurora Borelalis Aurora Borelalis

The Moon The Phases of the moon The Phases of the moon The Dark Side Moon The Dark Side Moon Lunar Eclipse Lunar Eclipse Tides Tides

Solar System Model Demonstration of the size and scale of our solar system Demonstration of the size and scale of our solar system

Constellations Identify the Great Bear, The Big Dipper, The Plough Identify the Great Bear, The Big Dipper, The Plough Identify the North Star (Polaris) Identify the North Star (Polaris) Orion and The Horse Head Nebula Orion and The Horse Head Nebula Taurus Taurus Plaeides Plaeides Casseopia Casseopia Star Maps Star Maps

Cosmology Mathematics Astronomical units (AU) Astronomical units (AU) Parsecs (pc) Parsecs (pc) Light years (ly) Light years (ly) Ellipses Ellipses

Cosmology 1Our Solar System How it all started…… ‘Geocentric’ Ptolemei & Aristotle Earth is the centre of the universe Copernicus (1609/1637) Present idea of planets rotating around the sun versus ‘Heliocentric’ Solar System

Cosmology Kepler’s Laws (1609) Describe the motion of the planets around the sun. Kepler I The orbit of a planet around the sun is an ellipse with the sun at one focus.

Kepler II 2 2A line joining a planet and the sun sweeps out equal areas in equal times. Click Picture for K2a Movie clack for K2b Movie

Kepler III Describes a relationship between the radius of the planets (average distance to the sun) and the time taken for one complete orbit. T 2 is proportional to R 3 Click for K3 Movie

Cosmology 1Our Solar System Kepler’s Laws (1609) Answer the following questions based on Kepler’s laws: 1a) Compare planetary ellipses to circles. In what way are they different? b) Use your worksheet ‘Structure and size of the universe’ to find out which planet is furthest off the circle and which one is closest to a circle. What about ‘Mars’- Kepler’s favourite…? c) Draw an ellipse with its two focal points and the two radii.

Cosmology 1Our Solar System Kepler’s Laws (1609) Answer the following questions based on Kepler’s laws: 2a) Use Kepler’s second law of equal areas describe the planets speed when its orbit is furthest from the sun and when its closest to the sun. b) Does the force that keeps the planet on its path change? Explain. 3How does the period of rotation of a planet change if the average distance to the sun a) doubles or b) triples.

The Big Bang Theory - Our Expanding Universe Cosmology is the search for origins. It seems as if everyone wants to know how the Universe began. Cosmology is the search for origins. It seems as if everyone wants to know how the Universe began. The Big Bang theory is the result of several important observations. The Big Bang theory is the result of several important observations. In 1927, Edwin Hubble first observed that light from distant galaxies is red shifted and that galaxies are moving farther and farther away from us. In 1927, Edwin Hubble first observed that light from distant galaxies is red shifted and that galaxies are moving farther and farther away from us. Second, he determined that the farther away a galaxy is from us, the faster it is receding from us. Second, he determined that the farther away a galaxy is from us, the faster it is receding from us.

Hubble’s Law What does this graph tell us? What does this graph tell us? Note how there is a clear proportionality between distance and recessional velocity. Note how there is a clear proportionality between distance and recessional velocity. This proportionality is known as the Hubble Law. This proportionality is known as the Hubble Law. The slope of this line, with dimensions of velocity over distance, is called the Hubble Constant (H). The slope of this line, with dimensions of velocity over distance, is called the Hubble Constant (H).

Recessional Velocity The graph shows that the recessional velocity (the speed a galaxy is moving away from us) is proportional to the distance from us. The graph shows that the recessional velocity (the speed a galaxy is moving away from us) is proportional to the distance from us. i.e. stars further away from us are moving away from us faster than stars closer to us! i.e. stars further away from us are moving away from us faster than stars closer to us!

What is the inference from Hubble’s Law Almost all Galaxies are red shifted and are thus moving away from us (The Milky Way) Almost all Galaxies are red shifted and are thus moving away from us (The Milky Way) The most Distant galaxies exhibit the most red-shift, thus the most distant galaxies are moving away from us fastest. The most Distant galaxies exhibit the most red-shift, thus the most distant galaxies are moving away from us fastest.

The Hubble Constant Let us look more closely at the slope of the Hubble Law Graph. Let us look more closely at the slope of the Hubble Law Graph. Slope = Velocity/Distance (Hubble Constant) Slope = Velocity/Distance (Hubble Constant) The inverse of the Hubble Constant then has the dimension of time, and can be taken as an estimate of the age of the Universe! The inverse of the Hubble Constant then has the dimension of time, and can be taken as an estimate of the age of the Universe! The Hubble Constant has been found to be between 50 and 100 km/s per kiloparsec. The Hubble Constant has been found to be between 50 and 100 km/s per kiloparsec. The Universe has thus been expanding for 8 to 15 billion years The Universe has thus been expanding for 8 to 15 billion years

The Future of the Universe? The gravitational attraction will eventually overcome the expansion. The Universe will stop expanding and then collapse to an eventual big crunch This is called a closed universe. The gravitational attraction will eventually overcome the expansion. The Universe will stop expanding and then collapse to an eventual big crunch This is called a closed universe. Alternatively the expansion slows to zero ‘at infinity’. This is called a flat universe. Alternatively the expansion slows to zero ‘at infinity’. This is called a flat universe. If there is not enough mass for its gravitation effect to overcome the expansion, the Universe will continue to expand forever. This is called an open universe. If there is not enough mass for its gravitation effect to overcome the expansion, the Universe will continue to expand forever. This is called an open universe. A closed universe might rebound forever – a big bang eventually resulting in a big crunch which rebounds into a big bang and so on. The whole Universe may be a gigantic oscillator! A closed universe might rebound forever – a big bang eventually resulting in a big crunch which rebounds into a big bang and so on. The whole Universe may be a gigantic oscillator! Don’t Worry - if there is to be a Big Crunch it won’t be for a very, very long time!