★ Star Guides ★

Stars & Star Systems

From our own Sun to the nearest Sun-like stars in our cosmic neighbourhood — in-depth guides to the science, history, and observing of individual stars.

2 Stars Covered
11.9 Light-Years (Nearest)
400bn+ Stars in the Milky Way

Star & System Guides

Comprehensive deep-dives into individual stars — their physics, history, planetary systems, and how to observe them from the UK.

The Sun (Sol)

G2V Yellow Dwarf 0 ly · Our Star
HD 173167 · Magnitude −26.7

The star at the centre of our Solar System — a middle-aged G-type yellow dwarf fusing 620 million tonnes of hydrogen every second. Explore its layers, sunspots, solar flares, and how to observe it safely.

Solar Activity Space Weather Safe Observing Aurora

Alpha Centauri

Triple Star System 4.37 ly · Southern Sky
HR 5459 / HIP 71683 · Magnitude −0.27

The closest star system to Earth — a triple system of two Sun-like stars and the faint red dwarf Proxima Centauri, the actual nearest star. Proxima hosts at least one confirmed rocky planet in its habitable zone.

Nearest Star System Proxima b Binary Pair Breakthrough Starshot

Tau Ceti (τ Ceti)

G8.5V Yellow Dwarf 11.9 ly · Naked Eye
HD 10700 · Magnitude +3.50

The nearest single Sun-like star in the sky — visible to the naked eye in Cetus. Home to intriguing planet candidates, a massive debris disc, and one of the longest SETI observation histories of any star.

Exoplanets SETI Habitable Zone Naked Eye

Sirius (α CMa)

A1V White Star 8.6 ly · Naked Eye
HD 48915 · Magnitude −1.46

The brightest star in the night sky — a blue-white binary system worshipped by ancient Egypt as the harbinger of the Nile flood. Its companion Sirius B, a white dwarf the size of Earth, was the first of its kind ever discovered.

Brightest Star Binary System White Dwarf Ancient Egypt

Barnard's Star

M4Ve Red Dwarf 5.96 ly · Binoculars
HIP 87937 · Magnitude +9.51

The closest single star to our Solar System and the fastest-moving star in the sky. A dim ancient red dwarf with a record-breaking proper motion of 10.36″/year — and a century of controversial planet claims that never quite held up.

Proper Motion Red Dwarf Project Daedalus Exoplanets

What Is a Star?

A quick primer on stellar classification and why individual stars are worth studying in depth.

A star is a giant, self-luminous ball of plasma held together by gravity and powered by nuclear fusion in its core. The Sun fuses hydrogen into helium at its centre, releasing energy that takes tens of thousands of years to reach the surface — and then just 8 minutes to travel to Earth. Stars range from tiny red dwarfs barely one-tenth the Sun's mass to blue hypergiants over 100 times larger, living only a few million years before exploding as supernovae.

Astronomers classify stars by their spectral type — a letter (O, B, A, F, G, K, M) that describes their surface temperature, colour, and chemical absorption lines. Our Sun is type G2V: a middling yellow dwarf. Tau Ceti is G8.5V — slightly cooler and dimmer, giving it a subtly more amber hue. Understanding individual nearby stars matters for astrobiology: the properties of a star fundamentally shape the chances of life on any worlds in orbit around it.

The Stellar Spectral Classes

The Harvard spectral classification runs from the hottest blue-white O stars to the coolest red M dwarfs. Most stars you can see with the naked eye are F, G, or K types.

O
Blue
>30,000 K
e.g. Naos
B
Blue-White
10,000–30,000 K
e.g. Rigel
A
White
7,500–10,000 K
e.g. Sirius
F
Yellow-White
6,000–7,500 K
e.g. Procyon
G
Yellow
5,200–6,000 K
e.g. Sun, Tau Ceti
K
Orange
3,700–5,200 K
e.g. Arcturus
M
Red Dwarf
<3,700 K
e.g. Proxima Cen