Where is Earth in the Milky Way? Our galactic address explained

Earth is inside the Milky Way’s disk, about 26,000–27,000 light-years (8.2–8.3 kiloparsecs) from the Galactic Center. That is roughly halfway from the center to the edge of the visible disk. The Solar System sits in a spiral feature called the Local Arm, also known as the Orion Arm or Orion Spur. It lies between the larger Sagittarius and Perseus arms and about 20 parsecs (about 70 light-years) above the disk’s midplane.

The Sun, carrying Earth with it, orbits the Galactic Center at roughly 230–250 kilometres per second. One full orbit, sometimes called a galactic year, takes on the order of 200–250 million years.

Key facts about Earth’s place in the galaxy

• Distance to the Galactic Center: 8,178 ± 13 (statistical) ± 22 (systematic) parsecs in 2019 and 8,275 ± 9 ± 33 parsecs in 2021, from GRAVITY Collaboration measurements; about 26,700–27,000 light-years.
• Spiral arm: the Local (Orion) Arm, more than 5 kiloparsecs long.
• Height above the midplane: 20.8 ± 0.3 parsecs (about 68 light-years) from a 2019 analysis of Gaia data.
• Orbital speed: circular rotation speed at the Sun’s distance of about 236 km/s; the Sun’s own speed around the center is about 247 km/s.
• Galaxy type: a barred spiral with a disk more than 100,000 light-years across.

Are we inside the Milky Way?

Yes. The Sun is one of the stars in the Milky Way’s disk, so every star you can see with the naked eye at night belongs to our own galaxy. NASA describes the Milky Way as a spiral galaxy whose stellar disk spans more than 100,000 light-years; the OpenStax Astronomy textbook classifies it more specifically as a barred spiral.

Being inside the galaxy has a cost: nobody can photograph the Milky Way from outside. Every map of its overall shape is reconstructed from measurements of distances and motions made from within, which is why some details remain uncertain.

How far is Earth from the center of the Milky Way?

About 8.2 kiloparsecs, or roughly 26,700 light-years; one parsec equals about 3.26 light-years. The most precise measurements come from watching individual stars orbit Sagittarius A*, the supermassive black hole at the Galactic Center. That black hole is about four million times the Sun’s mass. You can read more in our guide to what is at the center of the Milky Way.

The GRAVITY instrument at the European Southern Observatory’s Very Large Telescope Interferometer tracked the star S2 through its close passage of the black hole. Combining the star’s measured position on the sky with its line-of-sight speed gives a geometric distance. An independent method, using radio parallaxes of masers in star-forming regions, gives a consistent value.

Source note: GRAVITY Collaboration, Astronomy & Astrophysics 625, L10 (2019); Max Planck Institute for Extraterrestrial Physics summary of GRAVITY Collaboration 2021; Reid et al., Astrophysical Journal (2019). Light-year values use 1 pc = 3.2616 ly and are rounded.

The values differ by about 1%, slightly more than some of the quoted uncertainties. That gap shows how hard it is to control systematic errors even in the best measurements. Older figures such as “25,000 light-years” are rounded and less precise.

Which spiral arm is Earth in?

The Sun lies in the Local Arm, also called the Orion Arm or Orion Spur, between the Sagittarius and Perseus arms. It was long treated as a minor spur, but a 2013 study of maser parallaxes measured with the Very Long Baseline Array challenged that view. Xu and colleagues found that the Local Arm is more than 5 kiloparsecs long, has a shallow pitch angle of about 10°, and is actively forming stars. Those properties make it look more like a major arm. The authors suggested it might be a branch of the Perseus arm.

The overall pattern is still debated. A 2019 synthesis by Reid and colleagues described the Milky Way as a four-arm spiral, and astronomers continue to refine the number, shape and extent of the arms.

How far above the galactic plane is the Sun?

Slightly above it. A 2019 analysis of Gaia data by Morgan Bennett and Jo Bovy measured the Sun’s height above the local midplane as 20.8 ± 0.3 parsecs, or about 68 light-years, consistent with the textbook figure of about 70 light-years. Results depend on which stars or gas define the “midplane.” The Reid et al. maser study, for instance, found a smaller offset of 5.5 ± 5.8 parsecs. Either way, the Sun lies well within the thin disk, which is about 2,000 light-years thick.

How fast does the Sun orbit the galaxy, and how long is a galactic year?

Reid and colleagues measured the circular rotation speed at the Sun’s distance as 236 ± 7 km/s. Adding the Sun’s own extra motion gives about 247 ± 4 km/s around the Galactic Center. A rough orbital period follows from distance ÷ speed:

Orbit length = 2π × 8.2 kpc ≈ 1.59 × 10¹⁸ km
Period ≈ 1.59 × 10¹⁸ km ÷ 247 km/s ≈ 6.4 × 10¹⁵ s ≈ 204 million years

Using 236 km/s instead gives about 214 million years. Textbook and outreach figures vary: OpenStax gives about 225 million years at about 200 km/s, and NASA’s Imagine the Universe gives 250 million years. The spread reflects different rounded inputs and the fact that the Sun’s path is not a perfect circle. A fair summary is “roughly 200–250 million years.”

Why do we see the Milky Way as a band across the sky?

Because we see the disk from inside it. NASA explains that the band comes from seeing the disk of stars that forms the Milky Way from inside the disk. When you look along the plane of the disk, your line of sight passes through enormous numbers of distant stars whose light blends into a glowing strip. Look away from the plane and you see through far fewer stars.

The band does not appear because the Milky Way is a spiral; it would look like a band from inside any thin disk. Dust in the plane also blocks visible light. OpenStax notes that early star counts by William Herschel could reach only about 6,000 light-years because of interstellar dust, which is why much of the galaxy, including the Galactic Center, is hidden from view in visible light.

What have telescopes revealed about the Galactic Center?

The Event Horizon Telescope released the first image of any black hole’s shadow, M87*, on 10 April 2019. That black hole lies about 55 million light-years away in the galaxy Messier 87. On 12 May 2022 the same collaboration released the first image of Sagittarius A*, the Milky Way’s own central black hole, about 27,000 light-years from Earth. That image helped confirm that the object at our galaxy’s center is a black hole.

Which missions map the Milky Way today?

ESA’s Gaia spacecraft spent more than a decade measuring the positions, distances and motions of stars. It ended science observations on 15 January 2025 and was passivated (switched off) on 27 March 2025. Its work continues through data releases: Data Release 4, based on 66 months of observations, is planned for 2 December 2026, and the final release is expected no earlier than the end of 2030.

NASA’s Kepler space telescope is sometimes listed in this context, but it was an exoplanet survey, not a galaxy-mapping mission. NASA retired it on 30 October 2018 after it ran out of fuel; its archive is still used, including for estimates of how many planets the Milky Way contains.

Earth’s cosmic address

Source note: NASA Science (galaxies, Local Group); Xu et al. 2013; Bennett and Bovy 2019; GRAVITY Collaboration. For scale, see how far away the Andromeda Galaxy is.

What scientists don’t know yet

Astronomers still debate the exact number and shape of the Milky Way’s spiral arms, because the structure must be pieced together from inside a dusty disk. The distance to the Galactic Center is known to about 1%, but different methods still disagree slightly, and the Sun’s exact height above the midplane depends on how the plane is defined. Gaia’s upcoming releases are expected to sharpen all three.

Related reading

• What is in the center of the Milky Way? Sagittarius A* and the Galactic Center
• How long does it take to travel one light-year?
• How many planets are there in the Milky Way?

Update note: This article was substantially revised on October 12, 2026. The revision corrects the claim that the 2022 Sagittarius A* image was the first black-hole image (the first was M87* in 2019). It corrects the description of Kepler and Gaia as ongoing missions, and replaces the incorrect explanation of why the Milky Way appears as a band. It adds measured distances, height above the midplane, orbital speed and a worked galactic-year calculation. The off-topic habitable-planets section and an image whose reuse rights were questioned have been removed. It was drafted with AI assistance and checked against the sources listed below.

Sources

• GRAVITY Collaboration, A geometric distance measurement to the Galactic Center black hole with 0.3% uncertainty, A&A 625, L10 (2019)
• Max Planck Institute for Extraterrestrial Physics, The Massive Black Hole (GRAVITY 2021 distance)
• GRAVITY Collaboration, Improved GRAVITY astrometric accuracy from modeling of optical aberrations, A&A 647, A59 (2021)
• Reid et al., Trigonometric Parallaxes of High-Mass Star Forming Regions: Our View of the Milky Way, ApJ (2019)
• Xu et al., On the Nature of the Local Spiral Arm of the Milky Way, ApJ (2013)
• Bennett and Bovy, Vertical waves in the solar neighbourhood in Gaia DR2, MNRAS 482, 1417 (2019)
• OpenStax, Astronomy 2e, 25.1 The Architecture of the Galaxy and 25.3 The Mass of the Galaxy
• NASA Goddard, Imagine the Universe: Milky Way Galaxy
• NASA Science, Galaxies
• ESO, Astronomers reveal first image of the black hole at the heart of our galaxy (12 May 2022) and first image of a black hole (10 April 2019)
• ESA, Last starlight for ground-breaking Gaia; ESA Cosmos, Gaia passivation and Gaia data release scenario
• NASA, NASA Retires Kepler Space Telescope (30 October 2018)