The polarity of sunspot magnetic fields:
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Which layer of the Sun do we normally see?
Which layer of the Sun do we normally see?
Consider an atom of gold in which the nucleus contains 79 pr…
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight?
A light-year is:
A light-year is:
Study this H-R diagram. Which of the following stars has (or…
Study this H-R diagram. Which of the following stars has (or had) the longest hydrogen burning lifetime? (The red arrows help you locate these stars on the diagram.)
This photo shows an object located in the halo of our Milky…
This photo shows an object located in the halo of our Milky Way galaxy. What kind of object is it?
Open clusters and young stars are generally found only in th…
Open clusters and young stars are generally found only in the disk of the galaxy and not in the halo.
How does the light-collecting area of an 8-meter telescope c…
How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?
Which type of binary can have their sizes measured directly…
Which type of binary can have their sizes measured directly by photometry?
This diagram shows the life tracks from protostar to the mai…
This diagram shows the life tracks from protostar to the main sequence for several stars of different masses. Which track represents the star that takes the longest amount of time to reach the main sequence?