Astronomers and stargazers were looking to the dawn sky Friday as planets Mercury, Venus, Mars and Jupiter aligned over the southern hemisphere.

The visual treat was visible just above the horizon around sunrise.

Fred Watson, the astronomer-in-charge of the Anglo-Australian Observatory in NSW, said stargazers in eastern Australia should look to the sky between 5.00am and 7.00am (AEST).

He says Friday's planetary show may not be rivalled for another 29 years.

"Perhaps the best repeat performance of this - and one that will in some ways be even better - will be when all five of the naked-eye planets come together in the early evening sky on September 8, 2040," he said.

But he says Friday will not be the only chance to catch a glimpse of the alignment.

"It's one of these things that doesn't just take place over one day. This is something that's happened over a few weeks as the planets come together in the morning sky, and it will continue for a few weeks as they gradually drift apart again," he said.

Professor Watson says Venus will be in the middle of the group, while Jupiter will sit just above and to the left. Mercury will be to the right of Jupiter and slightly fainter.

"Venus is the brightest of all the planets and stunningly bright at the moment. Jupiter [will be] right next to it Friday morning, about half a degree away," he said.

"Then the other planets, Mercury and Mars, are sort of in accompaniment - Mercury's nearer than Mars is, and Mars is the one that is nearest to the horizon at the moment.

"That's four of the five naked-eye planets all in a fairly close-knit community in the early morning sky. What's special about this one is that they've come together in such a tight grouping."

Astrologer Douglas Parker believes the alignment has the power to influence behaviour and emotions down on Earth. He says his horoscope chart shows the four planets are actually very close to each other for about a week.

"Jupiter and Venus together indicates people born around this time will have film-star mannerisms, be extremely popular and have considerable artistic ability," he said.

"Mercury and Venus together indicates people born around this time will have considerable artistic and creative ability."

And, he says, it gets better.

"The Venus and Mars together in the sky indicates people born around this time will have a strong sexual magnetism and a strongly sensual nature," he said.

Astrologer Sarah Kulkens agrees the alignment will influence people down on Earth, but says it may not all be positive.

"The effect of this planet line-up has been slowly felt by many over the past few months and by the end of May people should be starting to slowly feel better," she said.

But Professor Watson says the alignment of the planets has no impact on human behaviour.

"The whole science community, not just astronomy, tells us that the planets have no direct influence on anything that goes on here on Earth," he said.

"The gravitational attraction of the planets, which is the only thing that could make any difference, is far too small to have any effect, unlike the moon which is a small object relatively nearby that does have an effect - it raises tides.

"The ancient tradition of trying to say that planets influence people will take great notice of the alignment of the planets, but from an astronomical and scientific point of view, and might I say from a reasonable point of view, they have no impact whatsoever."