How Many Planets Are There? From Our Solar System to the Whole Universe

It sounds like a simple question, but the answer depends on where you draw the line. Inside our own solar system the count is short and official. Beyond it, astronomers have confirmed thousands of planets and estimate there are billions more in our galaxy alone. Here is a plain-English guide to the numbers and how scientists arrived at them.

The planets of our solar system: eight

Since 2006 the official answer for our solar system has been eight planets. In order from the Sun they are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The first four are small, rocky worlds. Jupiter and Saturn are gas giants, made mostly of hydrogen and helium. Uranus and Neptune are often called ice giants because they contain large amounts of water, ammonia and methane.

What happened to Pluto?

Pluto was counted as the ninth planet from its discovery in 1930 until August 2006. That year the International Astronomical Union (IAU), the body that names and classifies objects in space, adopted a formal definition. A planet must orbit the Sun, be massive enough for its own gravity to pull it into a nearly round shape, and have “cleared the neighbourhood” around its orbit of other similar objects.

Pluto meets the first two tests but not the third: it shares its region of space with many other icy bodies in the Kuiper Belt. It was reclassified as a dwarf planet. The IAU currently recognises five dwarf planets: Ceres, Pluto, Eris, Haumea and Makemake. Many astronomers expect more small worlds in the outer solar system to qualify in future.

How far does our solar system reach?

The original version of this post confused a few distances, so it is worth setting them straight. Neptune, the outermost planet, orbits about 4.5 billion km (30 times the Earth-Sun distance) from the Sun. Pluto averages about 5.9 billion km. NASA’s Voyager 1 spacecraft, launched in 1977, crossed into interstellar space in 2012 and is now more than 24 billion km from Earth and in November 2026 reaches about one light-day away (roughly 26 billion km). That is a long way, but it is nowhere near “the edge of the universe”: it is still deep inside our own neighbourhood of the Milky Way.

Planets around other stars: more than 6,000 confirmed

A planet outside our solar system is called an exoplanet. The first exoplanet found orbiting a Sun-like star, 51 Pegasi b, was announced in October 1995. Since then the tally has grown rapidly. NASA’s count of confirmed exoplanets passed 6,000 in 2025 and stands at more than 6,300 in late 2026, with thousands more candidates waiting to be confirmed.

Most were found by two methods. The transit method watches for a tiny, regular dip in a star’s brightness as a planet passes in front of it; NASA’s Kepler and TESS missions found thousands this way. The radial velocity method detects a star wobbling slightly as an orbiting planet tugs on it. Other techniques include direct imaging and gravitational microlensing.

What kinds of planets are out there?

Exoplanets come in far more varieties than our solar system suggests. NASA groups them into gas giants, Neptune-like worlds, “super-Earths” (rocky planets larger than Earth) and terrestrial planets. There are “hot Jupiters” orbiting closer to their stars than Mercury does to the Sun, lava worlds, and planets with densities as low as foam. The TRAPPIST-1 system, about 40 light-years away, has seven Earth-sized planets. Some planets do not orbit a star at all: these rogue planets drift through the galaxy on their own.

So how many planets are there in total?

Nobody can count them all, but surveys allow good estimates. Studies of how often stars host planets suggest that, on average, there is at least one planet for every star in the Milky Way. NASA states simply that “there are more planets than stars in the galaxy.” With an estimated 100 billion to 400 billion stars in the Milky Way, that implies hundreds of billions of planets in our galaxy alone.

A 2016 study based on Hubble surveys estimated that the observable universe contains about two trillion galaxies, roughly ten times the earlier estimate of 200 billion, though most of those are inferred from models because they are too faint to see. Multiply that out and the number of planets becomes astronomically large, well beyond any practical count. That is the honest answer: our solar system has eight, we have confirmed more than 6,000 elsewhere, and the true total is uncountable but almost certainly enormous.

Can you see other planets yourself?

You can easily see five planets of our own solar system with the naked eye: Mercury, Venus, Mars, Jupiter and Saturn. They look like bright “stars” that shine steadily rather than twinkle and slowly move against the background constellations. With a small telescope Uranus and Neptune become visible as tiny discs. Exoplanets are far too faint and too close to their stars to see directly in amateur telescopes, although skilled amateurs do measure exoplanet transits and even contribute to NASA’s Exoplanet Watch citizen-science project.

Quick facts

• Planets in our solar system: 8 (IAU definition, 2006).
• Official dwarf planets: 5 (Ceres, Pluto, Eris, Haumea, Makemake).
• Confirmed exoplanets: more than 6,000 (NASA, 2025-2026).
• Estimated planets in the Milky Way: probably more than the number of stars.