-Explain how and when the universe formed according to the big bang theory?

-Explain how and when our solar system formed?
-Describe one observation astronomers use to show that the universe is Expanding?

According to the Big Bang theory, the universe originated from an extremely hot and dense state approximately 13.8 billion years ago. The theory suggests that all matter and energy in the universe were concentrated in an infinitesimally small point known as a singularity. Then, an event called the Big Bang marked the beginning of our universe, causing an explosion-like expansion. As the universe expanded, it cooled down, and matter gradually started forming, eventually leading to the creation of galaxies, stars, and other celestial structures.

The formation of our solar system is believed to have occurred around 4.6 billion years ago. It is thought to have begun with the collapse of a giant molecular cloud, composed mainly of hydrogen and helium, due to gravitational forces. As the cloud collapsed, its center formed a rotating protostar, known as the solar nebula. This protostar gradually grew hotter and denser, causing it to flatten into a spinning disk of gas and dust. At the center of this disk, the Sun was formed, while the leftover material in the disk began to accrete and form planets, including Earth.

One observation that supports the concept of an expanding universe is the phenomenon known as redshift. Astronomers have found that light from distant galaxies, traveling across space, appears to have its wavelengths stretched towards the red end of the light spectrum. This is known as redshift. The amount of redshift observed in the light from distant objects is directly proportional to their distance from us. This observation suggests that galaxies are moving away from us, and as a result, the universe is expanding. This idea is consistent with the predictions of the Big Bang theory and the concept of the universe's ongoing expansion.

We do not do your homework for you. Although it might take more effort to do the work on your own, you will profit more from your effort. We will be happy to evaluate your work though. However....

Since this is not my area of expertise, I searched Google under the key words "science big bang theory facts" to get these possible sources:

https://www.google.com/search?client=safari&rls=en&q=science+big+bang+theory+facts&ie=UTF-8&oe=UTF-8&gws_rd=ssl

In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.

http://www.hackcollege.com/blog/2011/11/23/infographic-get-more-out-of-google.html

Don't just copy the material. Express the ideas in your own words. Although this will take more time and effort, you will learn more.