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Scientists have provided the first look at what they called the "gentle giant" lurking at the centre of our Milky Way galaxy, unveiling an image of a supermassive black hole that devours any matter wandering within its gargantuan gravitational pull.

The black hole - called Sagittarius A*, or SgrA* - is only the second one ever to be imaged.

The feat was accomplished by the same Event Horizon Telescope (EHT) international collaboration that in 2019 unveiled the first-ever photo of a black hole - that one residing at the heart of a different galaxy.

University of Arizona astronomer Feryal Ozel, at a news conference in Washington DC, hailed "the first direct image of the gentle giant in the centre of our galaxy," showing a glowing ring of red, yellow and white surrounding a darker centre.

Sagittarius A* (pronounced Sagittarius "A" star) possesses four million times the mass of our sun and is located about 26,000 light-years - the distance light travels in a year, 9.5 trillion km - from earth.

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.

"This image shows a bright ring surrounding the darkness, the telltale sign of the shadow of the black hole," Ozel said.

"Light escaping from the hot gas swirling around the black hole appears to us as the bright ring. Light that is too close to the black hole - close enough to be swallowed by it - eventually crosses its horizon and leaves behind just a dark void in the centre."

"It turned out to be a gentler, more co-operative black hole than we had hoped for in the past decade of simulating its environment," Ozel added.

"We love our black hole."

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.

Harvard-Smithsonian Center for Astrophysics astrophysicist Michael Johnson called the black hole "ravenous but inefficient," eating relatively little matter.

The image released in 2019 of the supermassive black hole in a galaxy called Messier 87, or M87, showed a glowing ring of red, yellow and white surrounding a dark 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.

The researchers said that Sagittarius A*, despite being much closer to our solar system than M87, was harder to image.

The diameter of Sagittarius A* is about 17 times that of the sun, meaning it would sit within the innermost planet Mercury's solar orbit.

In contrast, M87's diameter would encompass the entirely of our solar system.

"Sagittarius A* is over a thousand times less massive than the black hole at M87, but since it is in our own galaxy it is much closer and should appear just slightly larger on the sky," said radio astronomer Lindy Blackburn, an EHT data scientist at the Harvard-Smithsonian Center for Astrophysics.

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.

Thursday's announcement was made in simultaneous news conferences in the United States, Germany, China, Mexico, Chile, Japan and Taiwan.

© RAW 2022

It took Tom Cruise 36 years to head back to the danger zone to bring a Top Gun sequel to the screen, and the first reviews from movie critics said it was well worth the wait.

Top Gun: Maverick earned a 96 per cent positive rating on the Rotten Tomatoes review aggregation website, which had collected 75 reviews as of Thursday afternoon. The movie debuts in theatres on May 27.

Cruise returns in the film as Pete Mitchell, the cocky navy pilot, codenamed Maverick, who has never risen through the ranks because of his penchant for bucking authority.

Mark Kennedy of the Associated Press called the movie "a textbook example of how to make a sequel".

"The movie satisfies with one foot in the past by hitting all the touchstones of the first film," Kennedy said, "and yet stands on its own."

Box office analysts predict the movie from Paramount Pictures will rank as one of the biggest box office hits of the summer. The movie had been scheduled for release in June 2020, but Paramount delayed its debut multiple times during the COVID-19 pandemic.

Shawn Robbins, chief analyst at BoxOffice Pro, said ticket sales would hit $US100 million ($A146 million) over the Memorial Day weekend in the US and Canada. That would make it highest-grossing debut of Cruise's career.

Critics said the movie offers thrilling flight scenes, an emotional story and strong performances by the supporting cast including Miles Teller, who plays the son of Goose, Maverick's partner who died in the original 1986 film.

But most of the praise was showered on Cruise.

"It's a fresh-faced gloss on the original ... powered, like the original, by a star who'll simply never stop being a star," wrote K Austin Collins of Rolling Stone.

Leah Greenblatt of Entertainment Weekly said the movie "belongs in almost every scene to Cruise".

"At this point in his career, he's not really playing characters so much as variations on a theme - the theme being, perhaps, The Last Movie Star," she said. "And in the air up there, he stands alone."

© RAW 2022

Anthony Albanese will turn his election campaign attention to one of the seven wonders of the natural world.

The Labor leader visits Cairns on Friday to announce extra funding to help save the Great Barrier Reef, pledging to work with the Queensland government, Indigenous communities, businesses and landowners.

"Parents and grandparents are worried their children will not be able to see this incredible natural wonder for themselves," Mr Albanese said.

"That's why it's so important we act on climate change and species protection - to protect the reef and the tens of thousands of jobs that rely on it."

In January, Labor pledged $163 million in funding for a reef protection program.

The additional announcement brings the total commitment to $194.5 million over the forward estimates.

As part of Labor's plan, Indigenous ranger organisations will be allocated $100 million by the end of the decade for reef protection and restoration programs.

Labor will work with the state government to scale up gully and wetland restoration and expand a crown-of-thorns starfish culling program.

The plan also includes funding to research thermal tolerant corals to help the species adapt to climate change.

Mr Albanese said seeing the Great Barrier Reef in person was a highlight for many Australians and international tourists.

He's expected to make the announcement alongside Queensland Premier Annastacia Palaszczuk.

Scott Morrison visited Cairns in January to commit $1 billion over the next nine years to help manage the reef after the Commonwealth successfully lobbied UNESCO to delay a decision listing the site as "in danger".

Meanwhile, the government is playing up its border protection credentials, saying if it's re-elected on May 21 it will pass new laws to charge foreign criminals for the cost of their own immigration detention.

"We don't believe foreign criminals deserve free rent, food and medical treatment while we go through the process of deporting them," Immigration Minister Alex Hawke said in a statement on Friday.

"We have cancelled or refused visas to over 10,000 serious criminals through our reforms to the character test and as we go through the process of deporting even more, the free ride they are getting now ends."

Labor is happy to look at the proposal, Tanya Plibersek says. But the senior Labor MP questioned the timing of the announcement.

"Isn't it interesting that the government has been there for almost a decade. This guy has been prime minister for three years, before being treasurer he was the immigration minister," she told Sky News.

"He could have done it at any time. Now a week out from an election he's come up with this brilliant new idea and everyone has to fall in line immediately. It looks a bit like a policy that's been dreamt up for a political campaign.

"(But) of course we will look at sensible proposals. We will consider the proposals thoroughly and thoughtfully."

Ms Plibersek reaffirmed Labor's commitment to boat turnbacks, saying there would be no tolerance for people smugglers.

Day 33 of the campaign will also see the prime minister promising to secure modern manufacturing and supply chains in Australia.

A $324 million pledge will safeguard Australia's supply chains seen as key to prosperity, resilience and national security.

It includes $15 million for a monitoring support mechanism to help predict future shocks to the system.

The CSIRO will be funded $4 million to enhance its transport network tool, which models domestic supply chains in Australia.

In addition, a $53 million investment will go towards building an animal health vaccine research and manufacturing facility.

The funding will establish an Animal Health and Manufacturing Innovation Hub and ensure supply of vital animal health products.

© AAP 2022