1. how does the life cycle of a star compare to that of a human? 2. what is the likelihood that black holes exist in our galaxy? explain your response. 3. how do massive stars change the atmosphere? 4. how are constellations an important part of history? 5. what is nuclear fusion? why is this process important to stars?

Hi!

1. A star comes into formation when the force of gravity pulls in clouds of dust and and various elements to accumulate, resulting in a buildup of pressure. This pressure, when high enough to overcome the repulsive forces prevalent between electrons, causes the nuclear fusion between two hydrogen atoms (light elements) to result in a helium atom. Massive amounts of energy are released as a result of this fusion reaction, which in turn drives nuclear fusion of other hydrogen atoms. The energy from these fusion reactions exert an outward pressure, as opposed to the gravity exerting an inward pressure on the elements, and this balance is what makes a star stable. This is different to the life cycle of a human, in that instead of two hydrogen nuclei fusing together, two sex cells (the egg and the sperm) fuse together to give rise to zygote, which further undergo mitosis to develop.

2. The likelihood of the existence of black holes in our galaxy is great. A black hole is considered to be the result of when a high mass star dies in a supernova explosion (when its 'fuel' runs out), and the effect of gravity causes the matter to collapse as there is no longer an outward force countering gravity. This results in a an intensely dense entity which is known as black hole. Although scientists cannot directly observe observe black holes, our evidence comes from how these entities influence matter around them, detected through emissions of high radiation as they absorb matter. The existence of black hole is what explains what happens to a star after it dies.

3. Massive stars, which are about 1.5 times larger than the Sun contribute to the critical mass of the supernova when they die out. Unlike the Sun which only produces helium and hydrogen, these massive stars create carbon, nitrogen and oxygen which are integral components of our own atmosphere, thereby influencing a change in the atmosphere by changing the concentration of these gases.

4. Constellations have served an important part of history as back in old times, before the advent of compasses and navigation tools, constellations were the only means by which people navigated through the seas, and even during journeys across lands. Constellations have been studied and observed by various cultures, including the Greeks and the Romans, and have been named after myths, legends, astronomers and historical people. Some constellations also have tales associated with them which have been told from generation to generation, such as the tale of Orion.

5. Nuclear fusion is a process in which two or more nuclei fuse/come together in a reaction to form a single heavier atomic nuclei, releasing massive amounts of energy in the process. Nuclear fusion is the process which runs the stars in that the energy produced as its result is the force that counters the inward pull of the gravity, preventing the star to collapse on itself and and die out. Without nuclear fusion, the star would not be able to sustain itself.

Hope this helps!

layers of the earth affect the waves and these effects are seen on instruiments such as seimometers

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