1.
What is the outermost layer of the sun?
Correct Answer
C. Photosphere
Explanation
The outermost layer of the sun is called the photosphere. This is the layer that emits the visible light that we see from Earth. It is also the layer where sunspots, solar flares, and other solar phenomena occur. The photosphere has a temperature of about 5,500 degrees Celsius and is composed mainly of hydrogen gas. It is the layer that we commonly refer to as the "surface" of the sun, even though it is not a solid surface like the Earth's.
2.
What layer of the Sun is the hottest?
Correct Answer
D. Core
Explanation
The core of the Sun is the hottest layer. It is the central region where nuclear fusion occurs, releasing enormous amounts of energy in the form of heat and light. The temperature in the core can reach up to 27 million degrees Fahrenheit (15 million degrees Celsius), making it the hottest part of the Sun.
3.
Which of the following is NOT a layer of the Sun's atmosphere?
Correct Answer
D. Core
Explanation
The Sun's atmosphere is divided into three distinct layers. The photosphere is the visible surface, emitting the light we see. Above it lies the chromosphere, a reddish layer usually only seen during eclipses. The outermost layer is the corona, a superheated plasma extending far into space, also best observed during eclipses.
4.
Which of the following does not occur in nuclear fusion?
Correct Answer
C. Mass is gained
Explanation
In nuclear fusion, lighter atomic nuclei, such as hydrogen isotopes, combine to form a heavier nucleus, such as helium. This process releases a tremendous amount of energy, as some of the mass of the original nuclei is converted into energy according to Einstein's famous equation E=mc². The energy released powers stars like our Sun.
5.
Why does nuclear fusion only happen in the core?
Correct Answer
A. The core is very hot
Explanation
Nuclear fusion only happens in the core because it is very hot. Fusion occurs when atoms collide with enough energy to overcome the electrostatic repulsion between their positively charged nuclei. The high temperature in the core provides the necessary energy for these collisions to happen, allowing fusion reactions to take place.
6.
Why can larger stars fuse larger atoms together?
Correct Answer
C. They have a higher pressure so they have a higher temperature
Explanation
Larger stars have a higher pressure due to their immense gravitational pull. This increased pressure leads to a higher temperature within the star. The higher temperature allows for the fusion of larger atoms because it provides the necessary energy to overcome the electrostatic repulsion between the positively charged nuclei. Thus, the higher pressure in larger stars results in a higher temperature, enabling the fusion of larger atoms.
7.
What is the largest element the Sun will be able to make?
Correct Answer
C. Oxygen
Explanation
The Sun is a massive ball of gas, primarily composed of hydrogen and helium. Through the process of nuclear fusion, hydrogen atoms in the Sun's core combine to form helium. Eventually, when the Sun exhausts its hydrogen fuel, it will start fusing helium atoms to produce heavier elements like oxygen. Therefore, oxygen is the largest element the Sun will be able to make.
8.
The hottest stars in the sky are large. What color are most of these very hot stars?
Correct Answer
B. Blue
Explanation
The hottest stars in the sky are large and emit a high amount of energy. This energy is produced by nuclear fusion reactions in their cores, causing them to emit a bluish-white light. This is due to the high temperature of these stars, which causes them to emit shorter wavelength light, resulting in a blue color. Therefore, most of these very hot stars appear blue in color.
9.
Our Sun will eventually die off. What will it be at the point that it stops nuclear fusion?
Correct Answer
C. White dwarf
Explanation
When our Sun exhausts its nuclear fuel and stops nuclear fusion, it will transform into a white dwarf. A white dwarf is the final stage in the life cycle of a star like the Sun. It is a dense, hot, and compact stellar remnant that remains after the outer layers of the star are expelled into space. The core of the star collapses under its own gravity, while the outer layers form a planetary nebula. The white dwarf will gradually cool down over billions of years, eventually becoming a cold, dark object known as a black dwarf.
10.
Stars that are in the red giant region are considered ___________. (fill in the blank)
Correct Answer
C. Old
Explanation
Stars that are in the red giant region are considered old because the red giant phase is a later stage in the evolution of a star. During this phase, the star has exhausted its core hydrogen fuel and has expanded and cooled down. This typically happens to stars that are nearing the end of their life cycle. Therefore, stars in the red giant region are generally older stars.