The Earth and universe

Page 1

In our solar system there r 8 planets orbiting the sun and are as follow according to their size ( starts from smaller planets) : 1- Mercury 2- Mars 3- Venus 4- Earth 5- Neptune 6- Uranus 7-Saturn 8- Jupiter

The first 4 planets are called inner planets and the last 3 planets are called outer planets.

(Pluto is not a planet any more due to its small size)

Earth

The earth is one of 8 planets orbiting the sun.

the diameter of the earth is 12,800 km

The diameter of the sun is 109 times the earth's

Distance to nearest star is 4 light years

asteroids are are smaller than planets and orbits the sun and most of them are between Mars and Jupiter.

moons orbit planets. most of them are tiny, only few are as large as our moon which is sixth of the diameter of the Earth

Comets spend much of their orbital time far from sun, their size are similar to asteroids and are made of dust and ice, as they approaches the sun the ice melts which forms comet tail

Sun

Sun is the star of our solar system,and is nearly all the source of energy we receive

it was a mystery for many years as to where it came from, but now its understood that the nuclei fusion is the source of energy

In Nuclei Fusion, smaller nuclei comes together and forms larder nuclei for example the H2 nuclei are joined together to make Helium nuclei which realizes an enormous amount of energy.

In stars larger than our sun Helium nuclei can be fused together to create atomic nuclei, as the earth contain many of these larger atoms such as, Carbon, Oxygen, Iron and etc.. it suggests that our solar system was made from remains of an earlier star

Looking at sky

The radiation and light realized from galaxies stars, gives as information about how far they are and how they are changing, and in future it may allow as to find out if life exists on planets around these stars. (now its difficult to observe these lights and radiations in cities because light pollution interferes with observation)

Looking at sky with naked eyes we can see moon, stars, some planets and a few cloud patches called nebulae.

after invention of Telescope astronomers could see that some of the nebulae are millions of stars called galaxies

astronomer Copernicus (1473-1543) first suggested that the Earth moved around the Sun

according to his suggestion if earth moves around the sun then u would expect to see a different view of the stars at different time of the year. which is called parallax

astronomers could answer this question using more powerful telescope that nearby stars do seem to move during a year but the movement is very tiny.

parallax: is an apparent change in the position of an object resulting from a change in position of the observer

The second nearest star to us is Proxima Centauri. The Sun is the nearest.

It seems to move through an angle of 1.5 seconds between January and June

now telescopes are placed in the space such as the Hubble space telescope, they are above the light pollution, dust and clouds and can observe all the sky, though they are expensive to launch, and if anything goes wrong only astronauts can fix them.

our sun is 150 million KM away from us

distance to the 2nd nearest star from us is 4 light years and it takes 100,000 light years to cross the Milky way (our galaxy), so the diameter of our galaxy is 100,000 light years.

the most distant galaxies observed are 13,000 million light years away

How stars and planets are formed:

According to 1 theory, stars and planets are farmed as follow:

When gases falls together it gets hot

A star forms when its hot enough for a Nuclei Fusion reaction to start

this releases energy and keeps the star hot

the outer pressure of the expanding gases are controlled by the force of the star's gravity

Gravity pulls small amount of dust and gases together which form planets in orbits around the star

according this theory this happened around 5 billion years ago, which is quite recent in the history of Universe, which is currently believed to be 14 billion years old

How dinosaurs were destroyed.

Data shows that the dinosaurs died out at about the same time as a large crater was made in Mexico. this suggests that an asteroid collision may have killed off the dinosaurs, the asteroid impact would have created dust that blocked up the light n heat from sun.

Galaxies: are thousands of millions of stars, first it was thought that our galaxy was the only galaxy but later astronomers such as Edwin Hubble found that there are many other galaxies outside the Milky Way, which are all moving away from as

the beginning and end of the universe:

Hubble’s observations led to the ‘Big Bang’ explanation of the beginning of the Universe, and set a date for this at 14,000 million years ago.

Hubble's Law: astronomer Edwin Hubble measured the distance to other galaxies n also the speed with which they are moving away from us and found a correlation between these factors, which suggests that the speed in which galaxies are moving away from us is proportional to its distance from us.

New Page