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Composition Motion Role of Stars & Nuclear Fusion Astronomy

In This Lesson we Study About Composition Motion Role of Stars & Nuclear Fusion Astronomy

It is hard to see the motion of stars because of their extreme distance from us


Gravity makes a nebula more stable in a newly formed star


The H-R diagram is a comparison between what?

A star’s absolute magnitude and temperature

Stars emit different light types based on the ______________

Elements that they absorb

Hydrogen atoms do NOT repel each other within a star


What is responsible for making stars shine?


A star has __________________; it appears to be moving across the sky as a night progresses

Apparent motion

What happens during the main-sequence stage of a star’s life?

It cycles, appearing brighter and dimmer in turns

Emission lines are lines that are made when wavelengths of light are given off by cooling gases


______________ may explode with such intensity that they become part of other objects

Massive stars

What is the Morgan-Keenan Spectral Classification system?

A method of classifying stars by their temperatures and compositions

Sky maps show celestial spheres, including constellations


Which color of flames would represent the HOTTEST temperature emitted from a star?


The Big Dipper and the Little Dipper are officially named what?

Ursa Major and Ursa Minor

A neutron star that spins is known as what?

A pulsar

What are stars made from?

Stars are balls of burning gas made mostly from hydrogen and helium.

Why do stars appear to move across the sky?

Due to the Earth’s rotation, stars appear to move across the sky. The stars close to Earth appear to move, whereas the stars far away appear to be stationary.

What are sky maps? How are they made?

Sky maps help to locate, identify, name and plot stars/constellations. Astronomers create sky maps by sectioning the celestial sphere into 88 different areas. (Every portion of the sky belongs within a particular constellation.)

How does a star’s appearance change based on the elements inside it?

Stars are made of mostly hydrogen gas, but may include other elements (such as helium, or calcium). Elements in a star absorb different wavelengths of light, which emit different colors. As a result, astronomers can tell what elements comprise a star.

How were the Spitzer telescope pictures important to understanding stars?

The Spitzer telescope is an infrared telescope that can photograph different temperatures. In 2004, the Spitzer space telescope captured the first pictures of a star’s birth.

How does the life cycle of a star compare to that of a human?

Similar to humans, stars are born, grow up, and die. Nebulae (clouds of dust and gas) give birth to stars; a star is born when nuclear fusion of hydrogen into helium begins. When stars are grown up (also known as the main sequence phase), they are fueled by nuclear fusion of hydrogen for many millions of years. Small stars live longer than big stars because they burn up their hydrogen more slowly. When a star has used up its hydrogen, it enters “old age.” Small stars experience an anticlimactic death by becoming a white dwarf then cooling down and becoming a brown dwarf. Massive stars can experience a violent death by exploding in a supernova, which scatters the star’s remains across the galaxy. (If the exploding star is huge, it can create a black hole.) The matter spread by this explosion leads to the next generation of stars. When humans reach old age, their cells die off similar to the depletion of hydrogen in stars. Some humans die peacefully in their sleep, similar to small stars. Other humans die tragically, similar to exploding supernovas. Finally, just like in human families, as one generation of stars die the next generation is born.

What is the likelihood that black holes exist in our galaxy? Explain your response

Astronomers used to think that massive stars were rare, but recent research suggests that there are more massive stars than previously thought. Black Holes form when massive stars die in a supernova. The dying star becomes extremely tiny and dense; its gravity is so strong that not even light can escape, that it is why it is called a “black hole.” Black holes can grow larger by sucking in gas, dust and nearby stars; some black holes even suck in other black holes. Cosmologists believe that super-massive black holes exist at the center of most galaxies. Based on observations of star movement near the center of our galaxy, it is highly likely that the Milky Way has at least one black hole.

How do massive stars change the atmosphere?

Massive stars are responsible for the production of many elements including oxygen and carbon. Our sun, which is an average sized star, contains mostly hydrogen and helium. Massive stars experience nuclear fusion at a quicker rate than average stars which causes them to become hotter and create more energy. This excess heat and energy results in a supernova–or a big explosion, which distributes the massive star’s elements into the universe. Without massive stars, the earth’s atmosphere would not contain the necessary elements (oxygen and carbon) to sustain life.

How are constellations an important part of history?

Many ancient cultures (such as the Romans and Greeks) noticed arrangements of stars that made patterns, which they called constellations. The constellations are named after historical people, places, myths, legends, or astronomers. One of the most famous constellations is Orion, who was a mythological Greek hunter. Other famous constellations include the twelve zodiac signs. Constellations tell stories about the past and the future (depending on if one believes in astrology). They were especially important for predicting the coming of the seasons for agricultural planning, as well as, navigating ships across the oceans to discover new continents.

What is nuclear fusion? Why is this process important to stars?

Nuclear fusion occurs when multiple Hydrogen atoms are forced together, under extremely high pressure and temperatures, to form one Helium atom. Nuclear fusion is vital to stars because it is responsible for the massive amounts of heat and light energy that stars emit. Nuclear fusion takes place in a star’s core. When a star dies, its elements are scattered into the universe. Their remnants are to be used again in the birth of new stars.