The stunning observations, to be published later this month, offer the best proof yet that supermassive black holes - among the most enigmatic and powerful forces in the universe - really do exist.

By tracking the orbit of 28 stars inside our own Milky Way for more than 16 years, scientists in Germany were able to trace the most detailed portrait ever obtained of these invisible monsters.

Black holes are believed to be concentrated fields of gravity so powerful that nothing - not even light - can escape their grasp. The only way to perceive them is by observing their impact on neighbouring celestial bodies.

This one is known as Sagittarius A* (pronounced 'A star').

'The stellar orbits in the Galactic Centre show that the central mass concentration of four million solar masses must be a black hole, beyond any reasonable doubt,' Dr Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics near Munich, Germany said in a statement.

One 'solar mass' is equivalent to our Sun.

Researchers were also able to calculate with far greater precision Earth's distance from the centre of the Galaxy: 27,000 light years.

A light year is the distance light travels in a year, about 10 trillion kilometres.

'The centre of the Galaxy is a unique laboratory where we can study the fundamental processes of strong gravity, stellar dynamics and star formation,' Dr Genzel said.

'Sagittarius A* give us the most detailed view we will ever have of a supermassive black hole because of its proximity to Earth,' he said.

The interstellar dust that fills the Galaxy blocks our direct view of the Milky Way's central region in visible light, so astronomers used infrared wavelengths to penetrate the dust.

The position of the stars was measured with a precision six times greater than in previous studies, equivalent to seeing a coin from a distance of roughly 10,000 kilometres.

Observations were made using the SHARP camera at the European Southern Observatory's New Technology Telescope in Chile, and instruments aboard ESO's Very Large Telescope.

The research is to be published in an upcoming issue of The Astrophysical Journal. -- AFP