Cosmic size comparison
From Earth to giant stars: sizes that break the mind.
Our sense of size fails completely in the cosmos. Earth is tiny next to the Sun — and the Sun tiny next to the largest known stars. This comparison places celestial bodies side by side so you can grasp the true proportions with your own eyes.
How big is that, really?
Compare cosmic sizes to Earth — on a logarithmic scale.
Earth · 12,742 km
Our reference: the Earth.
From planet to hypergiant
If the Sun were a football, Earth would be a pinhead 26 metres away. Yet even the Sun vanishes next to stars like UY Scuti, which would swallow the Solar System out to Jupiter.
Why comparisons matter
Numbers like "700 solar radii" stay abstract. Only a direct visual comparison conveys how unimaginably large the universe — and how small our home planet — really is.
Frequently asked questions
What is the largest known star?
Currently Stephenson 2-18 is among the largest — over 2,000 solar radii. Replacing the Sun, it would reach far beyond Saturn’s orbit.
How big is the Sun compared to Earth?
The Sun is about 109 times Earth’s diameter. Roughly 1.3 million Earths would fit inside it.
Is Jupiter a failed star?
Almost: Jupiter is the largest planet but would have needed about 80 times its mass to ignite as a star.
How small is Earth in the universe?
Vanishingly small. Our galaxy alone has over 100 billion stars — and there are billions of galaxies in the visible universe.
Why do giant stars look small in the sky?
Because of their enormous distance. Even the largest star appears only as a point of light from Earth.
Is there an upper limit to star size?
Yes, very massive stars become unstable and shed their outer layers. The exact limit is an active research question.
The cosmos in your inbox
Once a week: the best of the universe, made simple.
Welcome gift: a cheat sheet of 50 cosmic facts. Preview the 50 facts →
- Every week
- Always free
- No spam