Astronomy essay

Q1.Describethe lifecycle of sun like stars, name of the various phases and theenergy source the sun uses in each phase.

Thesun is undoubtedly an essential energy supplier on earth. It is oneof innumerable stars located at the core of the solar system.Approximately three quarters of the mass of the sun is made ofhydrogen, with the rest containing mostly helium as well as muchsmaller amounts of heavier elements like carbon, oxygen, iron, andneon. The sun’s lifespan started approximately 4.6 billion yearsago, when it began to burn hydrogen to generate energy. This processis expected to continue for roughly the same period when the sun’ssupply of helium and hydrogen fuel will be exhausted (Williams N.P).

Justlike with the rest of the stars the life of sun originated from agiant cloud consisting of gas and dust. At this level, the sun wasjust a protostar with no nuclear fusion happening (Williams N.P). Theconstituents then compressed together until there was adequatepressure to initiate nuclear fusion.

Currently,the sun is on the main sequence phase of its life. At this stage,nuclear fusion reactions are taking place in the core of the sunfusing hydrogen into helium. About half of the core hydrogen hasalready been used up. Since the amount of hydrogen in the sun’score is limited, this process is not everlasting. Until now, the sunhas converted approximately hundred times earth’s mass into solarenergy and helium (Williams N.P). With more and more hydrogen beingconverted into helium, the core will keep on shrinking thus allowingthe sun’s outer layers to shift closer to its center and cause agreater gravitational force.

Infuture, the sun will exhaust its supply of core hydrogen fuel causingit to collapse gradually. This will result into a buildup of inerthelium ash causing the core to become denser and heated up, hencecause the sun to enlarge. When the sun gets to its maximum size,helium fusion will take place in the core, and the sun will releasemore energy and become hotter. As helium starts to fuse into carbon,the carbon in the sun will begin to disintegrate inward (WilliamsN.P).

Oncethe sun exhausts helium fuel, its end will begin because there willbe no more fuel to burn. The sun’s lighter elements will bepowerfully expelled into space hence it will lose its mass at a rapidrate and get cooler in temperature. It will however be very bright.Finally, only the dense core of the sun will remain containing onlythe heaviest elements that have fused throughout its lifespan. Nonuclear fusion is happening thus the sun will become cooler and onlyemit a part of light it previously did. Once the sun cannot generateany light or heat, its life will end as black dwarf.

Q2.Describe what a transit is and how Astronomers can use them to findplanets outside of our solar system.

Anastronomical transit is an event that happens when a celestial bodysuch as moon or a star, appears to travel directly in front ofanother celestial body hence obscuring it from view. A solar eclipseis a good example of a transit, whereby the moon seems to traveldirectly across the sun, making it obscure and darkens the sky (CainN.P). A transit is possible when three objects are aligned in asingle line, i.e. a nearer object, a far-away object, and anobserver. Other transits include transits of Venus and Mercury acrossthe sun’s surface.

Transitis an important technique used by astronomers to find out extra solarplanets that orbit other stars. For example, when a planet movesacross the face of a star, the light from the star is slightlydimmed. When the planet moves from the star, it brightens once again(Cain N.P). Therefore, an astronomer can be able to determine ifthere are planets orbiting the star by observantly measuring thestar’s brightness.


CainFraser. Transit. 15/09/2010. Web. 17/05/2016.

WilliamsMatt, The Life Cycle Of The Sun. 22/12/2015. Web. 17/05/2016.