List of largest stars

Stars come in many different sizes, and some are truly enormous! This list shows the largest stars we know of, measured by how wide they are compared to our Sun. The stars here are so big that if you could put one in your hand, it would swallow up the whole Earth many times over!

We measure these giant stars using the radius of the Sun as a unit. That means we say how many times bigger a star is than our Sun. Some of these stars are thousands of times bigger! They are found in different places across the universe, in various galaxies far from us.

These lists help scientists and space fans learn about the amazing sizes of stars. By studying these huge stars, we can understand more about how stars live, grow, and eventually die. It’s exciting to think about how big some of these stars really are!

Not to be confused with List of most massive stars. The unit of measurement used is the radius of the Sun (approximately 695,700 km; 432,300 mi).

Overview

Red supergiants are often thought of as the largest stars, but some stars can grow even bigger for short periods, such as during special events like LBV eruptions or luminous red novae. These luminous red novae can expand very quickly, becoming thousands to tens of thousands of times larger than the Sun in just a few months.

Scientists also study very old stars from the early universe that might have grown huge by gathering material very fast. These stars could have been many times larger than the Sun. Measuring exactly how big stars are can be tricky because it depends on how we look at them and what kind of light we use. Even so, these lists of big stars are still being researched and might change as we learn more.

Main article: LBV eruptions

Main articles: Luminous red novae, Population III, very early universe, largest known black holes

Angular diameters

We can measure how stars look in the sky using special tools called stellar interferometry. We can also learn about stars when the Moon passes in front of them or when two stars orbit each other and eclipse one another. Only a few big stars, like Antares and 119 Tauri, can be studied this way with the Moon. Examples of eclipsing stars include Epsilon Aurigae, VV Cephei, and V766 Centauri. It’s hard to know exactly where a star’s edge is because their outer layers are very thin and change depending on the kind of light we use to look at them.

There are still many questions about how big these stars really are, especially when we try to figure out how bright they are and how hot their surfaces are. Because of this, the sizes of stars can only sometimes be given as an average or a range of possible values. Different scientists might find different numbers, and these lists of star sizes are still being updated as we learn more.

Caveats

Measuring the size of huge stars is tricky because scientists can only estimate their sizes using special formulas. Also, figuring out how far away these stars are can be hard and sometimes changes over time. Some big stars also change size a lot, making it even harder to know exactly how big they are.

Some of these giant stars are very far away from us, in places outside our own galaxy, the Milky Way. These faraway stars might act a little differently than the biggest stars we know closer to home.

Lists

This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by editing the page to add missing items, with references to reliable sources.

The following lists show the largest known stars based on the host galaxy.

Note that this list does not include the candidate JWST dark stars, with estimated radii of up to 61 astronomical units (13,000 R_☉) or quasi-stars, with theoretical models suggesting that they could reach radii of up to 40,700 solar radii (189 au).

During some transient events, such as red novae or LBV eruptions the star's radius can increase by a significant amount.

Largest stars by apparent size

The following list shows the largest stars based on how big they appear in the sky from Earth. We measure this size using something called "angular diameter," which is measured in milliarcseconds. One milliarcsecond is a very small piece of the sky, equal to one-thousandth of an arcsecond. The list includes stars that appear larger than 13 milliarcseconds wide to us on Earth.

Main article: Apparent magnitude