M87*

At a glance

Key points

Its ring has stayed the same size for years while its magnetic field flipped.

• First black hole image (2019)
• 6.5 billion Suns
• Its magnetic field flipped between 2017 and 2021

An Earth-sized telescope

The EHT links radio dishes from Hawaii to the South Pole so that, together, they resolve detail as fine as an orange on the Moon. Each year's image is assembled from petabytes of recorded data.

A jet seen since 1918

In 1918 Heber Curtis at Lick Observatory noted a 'curious straight ray' running out of the core of M87. It is now known to be a jet of particles moving at close to the speed of light and stretching for thousands of light-years. The jet is thought to draw its power from the black hole's spin through magnetic fields threading the inner disc, which is why the EHT's maps of polarised light near the ring matter so much.

Ring and jet together

In 2023 a global radio array including ALMA and the Greenland Telescope imaged M87 at 3.5 mm, a longer wavelength than the EHT's. The picture showed, for the first time, the ring and the base of the jet in one image. The ring was about 50% wider than at 1.3 mm, which the team interprets as light from the surrounding accretion flow. Repeated EHT campaigns since 2017 show the ring's size holding steady while its bright side moves.

Observing it

M87 itself is an easy target for a small telescope, most easily seen in evening skies around May, near the heart of the Virgo galaxy cluster. Through the eyepiece it is a round, featureless glow; neither the jet's fine detail nor the black hole's shadow is visible, and the shadow can only be resolved by linking telescopes across the planet.

What we still don't know

How the magnetic field near the horizon launches the galaxy's jet, and why its polarisation flipped.

Missions

1. 2017–

   Event Horizon Telescope

   International collaborationActive

   Earth-sized radio interferometer at 1.3 mm; imaged M87* (2019) and Sgr A* (2022).

   Mission page (opens in a new tab)

2. 1990–

   Hubble Space Telescope

   NASA / ESAActive

   Ultraviolet to near-infrared imaging from low Earth orbit.

   Mission page (opens in a new tab)

Related entries

• Messier 87Giant elliptical with the first imaged black hole
• Sagittarius A*The black hole at the centre of the Milky Way
• Black holeEvent horizon · gravity light cannot escape

Sources

1. ESO: eso1907: first image of a black hole (opens in a new tab)
2. EHT Collaboration 2025, A&A 704:A91 (arXiv) (opens in a new tab)
3. EHT: polarization flips at M87* (opens in a new tab)
4. MPIfR: M87* one year later, a persistent shadow (Jan 2024) (opens in a new tab)
5. Lu et al. 2023, Nature (opens in a new tab)
6. NASA Science: Hubble Messier catalog: M87 (opens in a new tab)

Last reviewed 10 Oct 2026 against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.