Star Brightness & Distance

Question 1

The Sun appears much brighter in the sky than the star Sirius. The Sun is about 93 million miles from Earth, while Sirius is about 25 trillion miles away. Which statement best explains why the Sun looks brighter than Sirius?

Accepted Answer

The Sun is much closer to Earth, so its light has to travel a shorter distance and spreads out over a smaller area before reaching us.

Answer

The Earth’s atmosphere blocks more of Sirius’s light than it does the Sun’s light.

Answer

The Sun’s surface temperature is higher than Sirius’s, so it emits brighter light.

Answer

The Sun is larger than Sirius, so it produces more total light than Sirius does.

Question 2

The Sun is about 93 million miles from Earth and looks very bright in the sky. A distant star is about 100 light‑years away and looks faint. Which explanation best supports the idea that the difference in their apparent brightness is due to their distances from Earth?

Accepted Answer

Because the star is much farther away, its light spreads out over a larger area before reaching Earth, making it appear dimmer than the Sun.

Answer

Earth’s atmosphere blocks more light from distant stars than from the Sun, so the star looks dimmer.

Answer

The star is farther away, so it must produce less light than the Sun, causing it to look dimmer.

Answer

The Sun appears brighter because it is hotter than the distant star, not because of distance.

Question 3

The Sun looks much brighter in the sky than the star Sirius. Which statement best explains why the Sun appears brighter to us?

Accepted Answer

The Sun is much closer to Earth than Sirius.

Answer

The Sun is larger than Sirius, so it looks brighter.

Answer

Light from the Sun travels faster than light from Sirius, so it reaches us brighter.

Answer

The Sun produces more total light than Sirius, so it looks brighter.

Try three questions

The Sun appears much brighter in the sky than the star Sirius. The Sun is about 93 million miles from Earth, while Sirius is about 25 trillion miles away. Which statement best explains why the Sun looks brighter than Sirius?

The Sun is about 93 million miles from Earth and looks very bright in the sky. A distant star is about 100 light‑years away and looks faint. Which explanation best supports the idea that the difference in their apparent brightness is due to their distances from Earth?

The Sun looks much brighter in the sky than the star Sirius. Which statement best explains why the Sun appears brighter to us?

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