Question 1

Why is the Sun on the list?

Accepted Answer

Because the ranking is honest about what it measures. Apparent magnitude is how bright something looks from Earth, and by that measure the Sun beats everything else by a factor of ten billion.

Question 2

Are the brightest stars the nearest ones?

Accepted Answer

Some are and most are not. Sirius is bright because it is close; Rigel and Deneb are bright in spite of being hundreds or thousands of light years away, because they give off tens of thousands of times more light than the Sun.

Question 3

Does brightest mean the most luminous?

Accepted Answer

No. This ranks apparent magnitude — how bright the object looks from here — which mixes how much light it gives off with how far away it is. A modest star nearby outshines a monster across the galaxy, and the ranking says nothing about which is the greater object.

Question 4

Why do smaller numbers come first?

Accepted Answer

Because the magnitude scale runs backwards. It was built from the naked-eye classes of antiquity, where first magnitude was the brightest, and it kept that direction when it was made numerical — so the top of this list holds the lowest numbers, and the very brightest are negative.

Question 5

Why are some stars missing?

Accepted Answer

Because no magnitude is recorded for them here. Brightness is also not a single number for everything: a magnitude measured through one filter is not comparable with one measured through another, and every figure on this site says which band it belongs to.

Question 6

How many stars can be seen without a telescope?

Accepted Answer

About 6,000 across the whole sky, and half of those are below the horizon at any moment. From a town the number falls to a few dozen, because the limit is set by how much light the sky itself is putting out rather than by the eye.

Question 7

Why does a star's brightness change?

Accepted Answer

Some genuinely vary — pulsating stars, eclipsing pairs, stars with spots — and the figure here is a mean where that is the case. The rest of the variation a person notices is the atmosphere, which is also what makes stars twinkle and planets not.

Question 8

Which is the brightest star in the night sky?

Accepted Answer

Sirius, in Canis Major, at magnitude −1.46. It is bright mainly because it is close: 8.6 light years, which puts it among the nearest handful of star systems to the Sun. Many stars far more luminous than Sirius appear far fainter.

The brightest stars in the sky

COMMON QUESTIONS