Scientists are set to announce on Thursday what they call a "groundbreaking" Milky Way discovery in what could be the release of an image of the supermassive black hole lurking at our galaxy’s centre and devouring any matter wandering within its gargantuan gravitational pull.

The researchers are part of the Event Horizon Telescope (EHT) international collaboration that in 2019 unveiled the first-ever photo of a black hole. They have been concentrating recently on the black hole called Sagittarius A*, or SgrA*, at the heart of the Milky Way.

This monstrous object possesses 4 million times the mass of our sun and is located about 26,000 light-years - the distance light travels in a year, 5.9 trillion miles (9.5 trillion km) - from Earth. If the researchers indeed have managed to take a photograph of Sagittarius A*, it would be only the second black hole ever so pictured.

The EHT project three years ago released an image of the supermassive black hole at the centre of another galaxy called Messier 87, or M87, showing a glowing ring of red, yellow and white surrounding a dark centre.

Thursday’s announcement will be made in simultaneous news conferences at 9am EDT (1300 GMT) in the United States, Germany, China, Mexico, Chile, Japan and Taiwan. The researchers have declined to disclose the nature of the announcement ahead of time but in a news release called it a "groundbreaking result on the centre of our galaxy."

Black holes are extraordinarily dense objects with gravity so strong that not even light can escape, making viewing them quite challenging. A black hole’s event horizon is the point of no return beyond which anything - stars, planets, gas, dust and all forms of electromagnetic radiation - gets dragged into oblivion.

Project scientists have looked for a ring of light - super-heated disrupted matter and radiation circling at tremendous speed at the edge of the event horizon - around a region of darkness representing the actual black hole. This is known as the black hole’s shadow or silhouette.

The Event Horizon Telescope is a global network of observatories working collectively to observe radio sources associated with black holes. The project was begun in 2012 to try to directly observe the immediate environment of a black hole.

There are different categories of black holes. The smallest are so-called stellar-mass black holes formed by the collapse of massive individual stars at the ends of their life cycles. There also are intermediate-mass black holes, a step up in mass. And finally, there are the supermassive black holes that inhabit the centre of most galaxies. These are thought to arise relatively soon after their galaxies are formed, devouring enormous amounts of material to achieve colossal size.

The Milky Way is a spiral galaxy that contains at least 100 billion stars. Viewed from above or below it resembles a spinning pinwheel, with our sun situated on one of the spiral arms and Sagittarius A* located at the centre.

The M87 black hole is far more distant and massive than Sagittarius A*, situated about 54 million light-years from Earth with a mass 6.5 billion times that of our sun.