the earth & the beyond.pptx physics
TRANSCRIPT
The Earth & the Beyond By Aditi Atmasidha
In our solar system, nine planets circle around our Sun. The Sun sits in the middle while the planets travel in circular paths (called orbits) around it. These nine planets travel in the same direction (counter- clockwise looking down from the Sun's north pole).
Inner system contains Mercury, Venus, Earth and Mars. These four planets are closest to Sun.
Outer system contains Jupiter, Saturn, Uranus, Neptune & Pluto.
The inner planets are separated from the outer planets by the Asteroid Belt.
Introduction
Our Solar System
Day and night occur because of earths rotation. It turns dark outside when the sun is on the other side of earth. All of this happens during the 24 hour cycle.
http://www.youtube.com/watch?v=_TBvCmT8RDg
How Days & Nights occur?
The seasons are caused by the tilt of the Earth's rotational axis away or toward the sun as it travels through its year-long path around the sun.
The Earth has a tilt of 23.5 degrees relative to the "ecliptic plane" (the imaginary surface formed by it's almost-circular path around the sun). The tilt toward the sun is maximized during Northern Hemisphere summer in late June (the "summer solstice"). At this time, the amount of sunlight reaching the Northern Hemisphere is at a maximum.
In late December, on the date of the "winter solstice", the Earth's tilt away from the sun is maximized, leading to a minimum of sunlight reaching the Northern Hemisphere. The seasons, of course, are reversed in the Southern Hemisphere.
How do seasons occur?
Causes of season change
http://www.youtube.com/watch?NR=1&v=Gzr0Ju0kqko&feature=endscreen
Time Zones are a geographical world globe division of 15o each, starting at Greenwich, in England, created to help people know what time is it now in another part of the world.
What are Time zones?
Many of the objects you can see in the night sky are stars, large objects in space that produce light. Stars are so far away that their light does not reach us for years. As light from so far away passes through our atmosphere, it is moved around so that the star seems to twinkle.
What are stars?
A celestial body moving in an elliptical orbit around a star.
What are Planets?
Difference between stars & Planets
Stars
A star has its own light.
Stars twinkle at night.
The relative positions of the stars do not undergo any noticeable change.
Since the stars are very far away, the telescope can only make them look brighter but not larger.
A star has very high temperature.
There are billions of stars in the celestial sphere.
Planets
A planet has no light of its own. It shines by reflecting the light of the sun.
Planets do not twinkle. Since planets are very mush closer to the
earth than the stars are, their motion around the sun is noticeable as a daily shifting of their relative positions in the sky.
Most planets on the other hand are near enough to the earth to be magnified by the telescope.
Planets have low temperatures. There are only nine planets in the solar
system.
Venus is covered in clouds.
These clouds are about 10 miles (16.5 km) thick and begin about 50 miles (83 km) above the ground.
From the surface of a planet, clouds obscure sunlight. From up above, however, they reflect sunlight very brightly.
Venus reflects about 60-80 percent of the sunlight it receives.
Why do Venus shines?
The brightness of a star depends on its size , temperature
& its distance from the Earth.
Bright stars
Star Temperature Color Distance from Earth
Sun 6000 Yellow 8 light min
Sirius 11000 White 8.6 light years
Arcturus 4000 Orange 36 light years
Betelgeuse 3000 Red 520 light years
Spica 25000 Blue 220 light years
Some well known Bright Stars
Constellation
A group of stars forming a pattern that is traditionally named after its apparent form or identified with a mythological figure. For example Orion.
http://www.slideshare.net/joelmotuk/chapter-23-section-2-notes-the-moon-earths-satellite
http://www.youtube.com/watch?v=wW_vmnfTeWM
Moon: the Earth’s Satellite
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
What is Galaxy?
There are billions of Galaxies in the Universe. Some are very small with only a few million stars. While others could have as many as 400 billion stars, or even more. There are three kinds of Galaxies, Spiral, Elliptical, and Irregular. The only difference between the three is what shape they are.
The three types of Galaxy
GALAXIES
Our galaxy, the Milky Way, is typical: it has hundreds of billions of stars, enough gas and dust to make billions more stars, and at least ten times as much dark matter as all the stars and gas put together. And it’s all held together by gravity. Like more than two-thirds of the known galaxies, the Milky Way has a spiral shape. At the centre of the spiral, a lot of energy and, occasionally, vivid flare. are being generated. Based on the immense gravity that would be required explain the movement of stars and the energy expelled, the astronomers conclude that the centre of the Milky Way is a supermassive black hole.
General Information
Other galaxies have elliptical shapes, and a few have unusual shapes like toothpicks or rings. The Hubble Ultra Deep Field (HUDF) shows this diversity. Hubble observed a tiny patch of sky (one-tenth the diameter of the moon) for one million seconds (11.6 days) and found approximately 10,000 galaxies, of all sizes, shapes, and colours. From the ground, we see very little in this spot, which is in the constellation Fornix.
FORMATION
After the Big Bang, the Universe was composed of radiation and subatomic particles
General Information
COLLISIONS
The shapes of galaxies are influenced by their neighbours, and, often, galaxies collide. The Milky Way is itself on a collision course with our nearest neighbour, the Andromeda galaxy. Even though it is the same age as the Milky Way, Hubble observations reveal that the stars in Andromeda's halo are much younger than those in the Milky Way. From this and other evidence, astronomers infer that Andromeda has already smashed into at least one and maybe several other galaxies.
General Information
Just Pictures