474 days since start of observations
59.45 hours of lunar observations
46.8 TB of lunar images
33 NEO lunar impact events
NELIOTA impact flashes

Location of the impact flashes detected so far by NELIOTA.

Video coverage by


What are NEOs?

Near-Earth Objects or NEOs are meteoroids, comets or asteroids found in the neighborhood of the Earth. NEOs can pose a threat to humans, as they can damage artificial satellites and moreover, impact the Earth.


What is a lunar impact flash?

A NEO directed toward the Moon will impact the surface, as the Moon does not have an atmosphere that is significant enough to shield it from the impacting body. The impact causes a flash that usually lasts less than 1 second and is followed by the formation of a crater.  


Why monitor the Moon for lunar impact flashes?

Scientists are interested in understanding the size distribution and frequency of NEOs in order to assess the threat of small NEO collisions to orbiting spacecraft and to a future mission that ESA envisions sending to the Moon.


What is NELIOTA?

NELIOTA (NEO Lunar Impacts and Optical TrAnsients) is an ESA project that aims to determine the distribution and frequency of small NEOs via monitoring the Moon for lunar impact flashes. The NELIOTA project has established an operational system that is monitoring the Moon, using existing facilities at the National Observatory of Athens, in search of faint NEO impacts. The project started in February 2015 and will run until the end of December 2018.


What is the duration of the NELIOTA campaign?

The NELIOTA campaign began in March 2017 and will collect lunar images until the end of December 2018.


When does NELIOTA observe the Moon?

NELIOTA observes the dark, night-side of the Moon in order to discover flashes against a dark background. For this reason, we observe the Moon between lunar phases 0.1 and 0.4.


What instrument does NELIOTA use?

NELIOTA uses the recently upgraded 1.2m Kryoneri telescope (by DFM Engineering, Inc. in 2016), operated by the National Observatory of Athens at Kryoneri Observatory in the Peloponnese, Greece. A custom-made Lunar Imager was installed at the prime focus of the telescope. The Lunar Imager uses a dichroic beam-splitter to send light to two sCMOS Andor Zyla fast-frame cameras, fitted with R and I-band filters, respectively. These observe the Moon at a rate of 30 frames per second.