What's the Brightest Star in the Sky? Depends on the Season

What's the brightest star you can see with your naked eye? (We're assuming you don't have the Hubble Space Telescope in your backyard.) It depends on the time of year and where you are on the planet while looking up. In this case, Sirius is hogging the spotlight. Photographic by Tommy Hsu / Getty Images

The night sky has fascinated humans for centuries, with people incorporating the countless twinkling stars into various navigation methods, cultural traditions, religious movements and more. Among these, a select few stand out to viewers here on Earth as being the biggest and brightest. But which is the brightest star in the sky?

The answer, it turns out, is not straightforward. Because of the Earth's rotation and the tilt of its axis, the brightest star in the sky will actually depend on which hemisphere — northern or southern — you live in and which season you're currently experiencing. This is because the night sky changes throughout the year, so a star's position and the time it rises and sets will all impact how bright you perceive it to be.

That said, the the intrinsic brightness of a star doesn't change based on an observer's location. Astronomers use a magnitude scale to measure star brightness, where lower numbers indicate brighter stars. This measure remains constant, regardless of whether or not the star is prominently visible in your region.

To unpack all of this, let's discuss the brightest stars, including when they're most prominently visible in the northern or southern hemisphere.

Sirius: Winter (Northern Hemisphere), Summer (Southern Hemisphere)

As far as astronomers are concerned, Sirius is objectively the brightest star visible from Earth (apart from the sun, of course). To measure star brightness, they use the magnitude scale, where lower numbers indicate brighter stars. Sirius has a magnitude of -1.46, a lower magnitude than any other star in the night sky.

From mid-December to February, Sirius dominates the night skies. These months correlate to winter in the northern hemisphere and to summer in the southern hemisphere.

Because it's located in the constellation Canis Major (the Great Dog), a common nickname for Sirius is the "Dog Star." And at just 8.7 light years away, Sirius is not only the brightest star but also the single closest star to Earth (again, after the sun).

How to Spot Sirius

While Sirius is visible in both hemispheres for several months out of the year, it's most prominent from December to February.

To find Sirius in the northern hemisphere, look toward the southern horizon in the early evening during the winter months. If you can locate Canis Major, it's the brightest star in that constellation.

In the southern hemisphere, Sirius is visible high overhead in the summer months.

Canopus: Winter to Spring (Southern Hemisphere)

By late spring in the southern hemisphere, Sirius is no longer visible since it's moved too close to the sun from our perspective on Earth. This sunsetting of Sirius makes it possible for a new star to put on a show in the southern hemisphere: Canopus.

Located in the constellation Carina (a Latin term for the keel of a ship), Canopus becomes visible throughout the southern part of the sky in late summer and autumn. With a magnitude of -0.74, it's the second-brightest star astronomers have ever measured.

How to Spot Canopus

In the southern hemisphere's spring and summer months, look for Canopus high in the sky.

If you're in the northern hemisphere, Canopus is only visible near the horizon from the lowest latitudes, and the best time to look is February.

Alpha Centauri: Year-round (Southern Hemisphere)

Sirius may be the single closest star to Earth (again, after the sun), but Alpha Centauri is the closest star system to Earth, at a mere 4.37 light years away. It actually consists of three stars: Rigil Kentaurus, Toliman and Proxima Centauri.

Located in the constellation Centaurus (the Centaur), Alpha Centauri has a combined apparent magnitude of -0.1, making it the third-brightest celestial star.

How to Spot Alpha Centauri

In most of the southern hemisphere, Alpha Centauri never sets, meaning you can see it on just about any night with clear skies. Look for the configuration known as the Southern Cross. The crossbar will point the way toward a bright and yellowish star, which is Alpha Centauri.

The star system isn't visible from most of the northern hemisphere, but if you're in the southernmost regions, it appears as a bright point of light close to the horizon.

Arcturus: Spring (Northern Hemisphere)

Arcturus is a bright red giant in the constellation Boötes (from a Greek word meaning "herdsman"), and it's unique in that there are no other notable bright stars close to it in the night sky.

The fourth-brightest star, Arcturus (and its -0.05 magnitude) is easily visible year-round in most of the northern hemisphere. It's especially prominent between March and May and has an orange-red glow.

How to Spot Arcturus

In the northern hemisphere, first locate the Big Dipper constellation: The handle points directly toward Arcturus.

Arcturus is also viewable in the southern hemisphere but only in the spring and summer.

Vega: Summer (Northern Hemisphere)

As summer arrives in the northern hemisphere, Vega takes center stage. It's one of the brightest stars in the sky with a magnitude of 0.03. Summer is the best season in which to view it, although it's technically visible in the northern hemisphere year-round.

Vega actually belongs to a famous trio of bright stars: Astronomers have dubbed Vega, Altair and Deneb (all of which belong to different constellations) the Summer Triangle.

Located in Lyra (the Lyre or Harp constellation), Vega is about 25 light years away from Earth.

How to Spot Vega

To spot the star Vega in the northern hemisphere, look toward the northeast at mid-evening during May or directly overhead after sunset in July.

In the southern hemisphere, Vega might be difficult to observe because it doesn't reach its highest point until 3 or 4 o'clock in the morning. If you can stay up that late to catch a glimpse, May is the best month.

Capella: Winter (Northern Hemisphere)

Visible from late August to the middle of June in the northern hemisphere, Capella is most striking during the winter, when the bright star rises to prominence in the night sky. With a magnitude of 0.08, it is the sixth-brightest star astronomers have measured and is part of the constellation Auriga, or The Charioteer.

Capella is special in that it's not actually a single star but a quadruple star system, including two red giants. To viewers on Earth, the star gives the impression it's twinkling red, green and blue flashes of light as it rises or sets over the horizon.

How to Spot Capella

In the northern hemisphere, look for Capella in the northeast during the early evening from mid-October through March.

For most of the southern hemisphere, Capella is not visible at all.

Rigel: Winter (Northern Hemisphere), Summer (Southern Hemisphere)

Rigel is one of the brightest stars in the night sky and is located in the constellation Orion. With an apparent magnitude of 0.13, it's the seventh-brightest star in the sky.

Astronomers classify Rigel as a blue supergiant. It's extremely hot and luminous — about 10,000 times brighter than our sun — which is why it still appears so bright to viewers on Earth despite being 863 light years away.

If you can find Orion in the night sky, you can find Rigel, which represents Orion's right leg and twinkles blue-white.

How to Spot Rigel

In the northern hemisphere in the summer, you can spot Orion and Rigel in the east just before the sun comes up. However, it's a more spectacular view on winter nights, when it's high in the southern sky.

In the southern hemisphere, look for Rigel to be high overhead on summer nights. In January and February, it will be visible as soon as the sun has gone down.

We created this article in conjunction with AI technology, then made sure it was fact-checked and edited by a HowStuffWorks editor.