Module 16 Vocabulary
Terms in this set (29)
The process by which two or more small nuclei fuse to make a bigger nucleus.
The process by which a large nucleus is split into smaller nuclei.
The amount of isotope necessary to sustain a chain reaction.
The brightness of a star, corrected for distance, on a scale of -8 to +19. The smaller the number, the brighter the star.
The brightness of a star as seen in the night sky. The smaller the number, the brighter the star.
The substance light could travel along a straight line in one year.
A large ensemble of stars, all interacting through the gravitatational force and orbiting around a common center.
Four Regions of the Sun
Core, Radiative Zone, Convection Zone, and Photosphere
How does the sun get its power? In which region of the sun does the process occur?
The sun gets its power from nuclear fusion that occurs in the core.
What part of the sun do we see?
We see the photosphere.
A 251Cf nucleus is bombarded with a neutron. It breaks down into a 124 Sn nucleus, a 120 Cd nucleus and seven neutrons. Is this nuclear fission or nuclear fusion?
This is nuclear fission since the large nucleus splits into two smaller nuclei.
Two 4He nuclei colllide and turn into a 7Be nucleus and one neutron. Is this nuclear fusion or nuclear fission?
This is nuclear fusion since the two small nuclei become a bigger nucleus.
For both the nuclear fusion that occurs in the sun and the nuclear fission that occurs in a nuclear power plant, what can we say about the mass of the starting materials compared to the mass of what's made in the end?
The mass of the starting materials is larger than the mass of the materials the process makes. (mass in converted into energy)
Why is it impossible for a nuclear power plant to have a nuclear explosion?
A power plant does not have significantly more than the critical mass of the large nucleus that is breaking apart so it is impossible for it to explode.
Why is nuclear fusion considered a better option for energy production than nuclear fission?
Nuclear fusion is a better means of producing energy because there are no radioactive byproducts, there is no chance of meltdown, and the starting materials are cheap.
If nuclear fusion is a better option, why don't we use it?
We cannot use nuclear fusion yet because we cannot master the technology to make it economically feasible.
Which of the stars is most like our sun?
The star most like our sun is main sequence.
Order the four starts in terms of increasing size.
White dwarf, main sequence, red giant, super giant.
Oder the four starts in terms of increasing brightness.
white dwarf, main sequence, red giant, super giant.
Which of the stars is the coolest?
Red Giant is the coolest.
What similarity exists between novas, supernovas, and pulsating variables?
All three of these are variable start types. Thus, their brightness changes radically with time.
What is the big difference between novas, supernovas, and pulsating variables?
The big difference between these star types is lifetime. Pulsating stars last a long time, supernovas exist very briefly and novas are somewhere in between.
What most likely formed the crab nebula?
The crab nebula was most likely formed by a supernova .
What are th e two methods for measuring the distance from earth to a star? which of the two is the most accurate? Which can be used to measure long distances?
The two methods are the parallax method and the apparent magnitude method. the parallax method is exact, but the apparent magnitude method can be used to measure longer distances.
Why are Cepheid variables so important for measuring long distances in the universe?
Cepheid variables are important for measuring long distances because they seem to have a relationship between their period and their magnitude. That allows them to be used in the apparent magnitude method for measuring long distances in the universe.
What are the four basic types of galaxies? To which type does the Milky Way belong to?
Four galaxy types are spiral, lenticular, elliptical and irregular. The Milky Way is a spiral galaxy.
Fill in the blanks: Stars group together to form___________, which group together to form _______, Some of which group together to form _________.
Starts group together to form groups, which group together to form clusters, some of which group together to form superclusters.
Why do most astronomers believe the universe is expanding?
Most astronomers believe that the universe is expanding because the light from nearly every galaxy experiences a red shift before it reaches the earth, and the red shift increases the farther the galaxy is from the earth.
If the universe is expanding, does the geometry of the expansion matter? If so, why?
Yes,the geometry of the universal expansion makes a great deal of difference. The theories that can be developed for the formation of the universe depend on that initial assumption.