Science communication · Interactive
Neutrino telescopes of the world
Where the world’s neutrino telescopes are, and which part of the sky each one sees best. Hover a card to fly the globe to a telescope, then explore how each one’s view of the sky changes with the neutrinos’ energy.
A planetary network
Neutrino astronomy is only just beginning: IceCube’s first cosmic neutrinos in 2013, and the first sources traced since, have opened a new way to look at the most violent places in the universe. Seeing them well takes more than one telescope. Each sees best in its own band of directions near its horizon, so telescopes spread around the globe watch different parts of the sky, and together they cover nearly all of it.
Combined into a single, planet-wide instrument, the high-energy Planetary Neutrino Monitoring System (PLEnUM), these telescopes would cover almost the entire sky, and the chance of detecting a source could improve by up to a hundred times over what IceCube achieves alone. The rest of this page shows why: which part of the sky each telescope sees, and how it changes with the neutrinos’ energy.
Source: L. Schumacher et al., “PLEνM: A global and distributed monitoring system of high-energy astrophysical neutrinos”, Proc. 37th International Cosmic Ray Conference, PoS(ICRC2021)1185, arXiv:2107.13534.
- Running or being built
- Finished
- Planned or proposed
Hover a card, or click a marker, to fly there. Drag to turn the globe.
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P-ONE
Pacific Ocean, off Vancouver Island · 2,600 m deep
Under construction
The newest member: strings of light sensors in the deep sea at Cascadia Basin, built on Ocean Networks Canada’s seafloor observatory. Its first line, P-ONE-1, was tested in 2026.
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IceCube
South Pole, Antarctica · 1.5 to 2.5 km deep in ice
Running since 2010
A cubic kilometre of Antarctic ice, watched by 5,160 sensors. It discovered cosmic neutrinos in 2013. A much larger successor, IceCube-Gen2, is planned.
Website ↗ -
KM3NeT
Mediterranean Sea · off Sicily and off Toulon
Under construction, already taking data
Two detectors: ARCA, 3.5 km deep off Sicily, hunts cosmic neutrinos; ORCA, off southern France, studies how neutrinos change flavour. ARCA caught the most energetic neutrino yet.
Website ↗ -
Baikal-GVD
Lake Baikal, Siberia · about 1 km deep
Growing cluster by cluster
In the world’s deepest lake, using fresh water instead of sea water. It has been built up cluster by cluster, each winter from the frozen surface of the lake.
Website ↗ -
ANTARES
Mediterranean Sea, off Toulon · 2.5 km deep
2008 to 2022
The first full neutrino telescope in the sea, with 12 strings. It proved the idea worked and paved the way for KM3NeT, before being switched off in 2022.
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TRIDENT
South China Sea
Planned
A planned telescope in the deep western Pacific, larger than IceCube, now testing its site.
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HUNT and NEON
South China Sea and nearby
Proposed
Two further proposals for very large telescopes in the region, aimed at the highest-energy neutrinos.
Why one telescope cannot see the whole sky
A neutrino telescope does not see equally well in every direction. It sees best in a band of directions around its horizon, set by two filters: the matter above it, which screens out a confusing background, and the Earth below it, which can stop the neutrinos themselves. How much each filter lets through depends on the neutrinos’ energy, so the band moves as the energy changes. Slide the energy, and drag the globe to see the band from any side.
To see where each telescope looks, switch the figure to Earth and sky or Sky from inside: each band lands on the sky as a ring. As the Earth turns, the rings sweep round the sky, and sources drift through them.
View
At each telescope, the band of directions it sees best, drawn as two cones: the upper edge out into the sky, the lower edge down through the Earth to where its neutrinos go in.
Each band lands on the sky as a ring. Play a day to watch the rings sweep across the stars as the Earth turns.
The far half of the sky, seen from the Earth’s centre. Point at the stars, sources and neutrinos for their names.
Telescopes pick any
10 TeV1 PeV10 PeV
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A blazar: the first identified neutrino source A blazar is a galaxy whose supermassive black hole fires a jet almost straight at Earth. TXS 0506+056 lies about 4 billion light-years away. In 2017 IceCube detected a high-energy neutrino from its direction while it was flaring in gamma rays, the first evidence of a source of cosmic neutrinos.
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A nearby active galaxy hiding its core Also known as Messier 77, NGC 1068 is about 47 million light-years away. Dust hides the supermassive black hole at its center. In 2022 IceCube found evidence of neutrinos coming from it, more than its gamma rays would suggest. They are likely made in the dense region close to the black hole, where gamma rays are absorbed but neutrinos fly straight out.
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Our own Milky Way The dotted line is the disk of our galaxy as seen from Earth; the dot marks its center, about 26,000 light-years away, home to the black hole Sagittarius A*. In 2023 IceCube detected neutrinos from the galactic plane. Possible sources include supernova remnants and pulsars. Most of the plane lies in the southern sky, which telescopes in the northern hemisphere such as P-ONE see well.
Why the band sits near the horizonThe two filters, with the maths and its sources
A neutrino telescope sees best in a band of directions near its horizon. Two filters set the band’s edges: the water above the telescope screens out a flood of muons, and the Earth below stops some of the neutrinos themselves.
- Energy
- Upper edge
- above
- Lower edge
- below
These follow the energy slider in the figure above, as do the blue numbers below.
The upper edge
A shield of water against muons
Muons outnumber neutrinos a million to one. Cosmic rays hitting the atmosphere make them, and their tracks look just like a neutrino’s.
Water slows them down. A muon loses energy as it goes, a little to knocking electrons off atoms and, at high energies, much more to bursts of radiation:
−dE/dX = a + b Ea ≈ 0.27 GeV per metre of water, b ≈ 3.5 × 10⁻⁴ per metre
So it only gets so far. Adding that up gives a muon’s range:
R(E) = (1/b) ln(1 + b E / a)about 2.4 km of water at 1 TeV, 7.5 km at 10 TeV
The shield is thinnest straight up. At depth h (2.6 km for P-ONE), looking at an angle θ from straight up, there is this much water overhead:
X(θ) = h / cos θ2.6 km straight up, 5.2 km at 60°, 15 km at 80°
Higher energy, higher edge. The few muons that get through still drown out neutrinos from above, unless the neutrinos are energetic enough to stand out: muons thin out faster with energy (about E−3.7) than cosmic neutrinos (about E−2.5).
On this page: a rough illustration, not a simulation. The edge is level with the horizon up to 100 TeV, then rises 20° for every factor of 10 in energy, to match the published band at 1 PeV:
αup = 10° + 20° × log10(E / 1 PeV)kept between 0° and 45°. Now: E = , αup =