What is the brightest star in the sky?

When you look into the sky, it doesn't take more than a moment or two for the brightest stars to catch your attention. On a clear night, some of the brightest stars can look as though they are close enough for you to touch.

Have you ever contemplated which of the stars ranks as the brightest? You don't have to be an astronomer or scientist to have curiosity about the universe. The reality is that some stars are brighter than others, and there are precise reasons.

At Star Register, we get lots of questions about the many type of stars, how to name a star, and even the cost to buy a star.

This affords us the opportunity to educate novice stargazers like you about the magnificent universe around us.

In the following sections, we'll take a look at the five (5) brightest stars, identify them and give you some interesting information about why are some stars brighter than others.

Factors Used to Determine the Brightness of Stars

While looking up constellation names and picking out your favorite one, you might recognize that some stars are rated brighter than others. You might question why that is and what goes into determining the brightness of stars.

For centuries, astronomers have used specific guidelines to rate the brightness of twinkling stars. All space objects have their brightness rated using a magnitude scale. The magnitude scale has two ratings: apparent and absolute.

The apparent magnitude relates to how bright a star looks in the sky to the naked eye. It's fairly easy for someone with normal eyesight to determine which of many stars appears to be brighter. To properly compare the apparent magnitude of two stars, a person would need to be positioned at an equal distance from both stars.

The absolute magnitude is a bit more objective. It relates to the intrinsic luminosity, distance, and other factors that could act to reduce its brightness. As a rule of thumb, the lower a star's absolute magnitude, the brighter the star will look to observers.

Based on this brightness rating methodology, let's take a look at the five (5) brightest stars in the sky today.

1. The Sun

Novice stargazers don't normally recognize the sun as a star. The common mistake that people make is thinking a star is an object that only is seen at night. The reality is the sun does appear at night, though its most endearing quality is it lights up the planet as it rotates around it. Yes, this is true of every object in the galaxy that could be classified as a sun.

As the closest star to Earth, the sun has an apparent magnitude (-26.7) with an absolute magnitude of only +4.8.

It's worth noting that some organizations don't consider the sun to be a star. Therefore, the next star on this list is generally considered the brightest star in the sky to said organizations.

2. Sirius

Of all the stars in the sky, only a few have recognizable names. Sirius would be one of those stars. This star is located about 8.6 light-years away from Earth, making it the closest star other than the sun. This star has an apparent magnitude of -1.46 with a +1.4 absolute magnitude.

Sirius is also referred to as the dog star because of its place in the constellation Canis Major, the Greater Dog. It's worth noting that while Sirius is rated as the second brightest star, its standing as a luminous object is far exceeded by other objects and stars, including stars on this list.

3. Canopus

Canopus or Alpha Carinae holds a place in the constellation Carina, which is the easiest constellation to locate from the Earth's Southern Hemisphere. It has an apparent magnitude of -0.74 with an absolute magnitude of -4.7.

In the sky, Canopus will appear to be pure white to the naked eye. The fact is our third brightest star is 10,000 times more luminous than the Sun, is eight times as massive, and has a radius that measures 71 times the radius of the sun.

It's noteworthy that prior to the 20th century, Canopus was largely ignored by astronomers in the West. At issue was the fact astronomers saw the star as rather unspectacular in comparison to other stars. It ended up earning a class rating of F in 1897.

4. Alpha Centauri

Alpha Centauri (Rigil Kentaurus) is another star that's name is highly recognized all over the world. It was discovered sometime in the 2nd century. At 4.4 light-years from Earth, this star is considered to be the most prominent neighboring star to the sun.

It has an apparent magnitude of -0.1 with an absolute magnitude of +4.38. In comparison to the sun, Alpha Centauri has 1.1 times the mass and 1.5 times the luminosity while also being significantly cooler.

Interesting fact: Alpha Centauri is actually a three-star system with the three stars being this star, Alpha Centauri A, Toliman or Alpha Centauri B, and Proxima Centauri or Alpha Centauri C.

5. Arcturus

Arcturus is distinguishable from other stars because of its reddish color. Its coloring led it to be referred to as the giant red star in the sky. It has an apparent magnitude of -0.04 and an absolute magnitude of 0.2.

As part of the constellation Boötes (the herdsman), the star is mostly visible in the Northern Hemisphere of the Earth's sky. As bright and big as the star is today, many leading astronomers believe that Arcturus will eventually appear as nothing more than a "white Dwarf" object in the sky once it reaches the end of its longevity.

For the benefit of novice stargazers, the easiest way to locate Arcturus is to find the handle of the "Big Dipper," one of the most recognizable constellations in the world.

Hopefully, you have found this information to be interesting and useful. If you are interested in naming a star for a loved one, you might want to consider finding an available star that is close to a bright star. That would make it easier to locate on a clear night.