When Stars Explode

Part A

What are two main ideas of the article by Ken Croswell?

• Supernovae are violent explosions of stars.

• Astronomers did not always use telescopes.

• Astronomers can see supernovae for months.

• Stars make energy through nuclear reactions.

• Stars produce light that travels across the universe.

Part B

Which two sentences from the article best support the answer to part A?

• "Its center makes energy the same way the Sun does: by changing hydrogen, the lightest element, into helium, the second-lightest elment."

• "The last time people saw a supernova in our galaxy was 1604."

• "That was before astronomers were using telescopes."

• "If a supernova occurred within a few dozen light-years of Earth, we would be in trouble."

• "Such a star is born with more than eight times the mass of the Sun."

Read the sentence from the text.

But as long as the star can make energy, it can fight the force of gravity and survive.

Which dictionary entry best defines energy?

• Physical strength

• hydrogen and helium gas

• heavy metals that increase weight

• power that comes from heat

What are two possible main ideas?

• Supernovae make important elements.

• Only some stars will become supernovae.

• Hydrogen is the lightest element.

• Astronomers did not always use telescopes.

What are the two possible supporting details?

• "And the explosions themselves produce iron."

• "The last time people saw a supernova in our galaxy was 1604."

• "The Sun will never explode."

• "However, every year astronomers see supernovae exploding in other galaxies."