The Piscis Austrinids, Southern Delta Aquariids and Alpha Capricornids will illuminate skies from tonight.

Dr Andrew Jacob, curator at the Powerhouse's Sydney Observatory, said the timing of the showers is "as good as we're going to get".

"The new moon is coming up on Friday, so these meteors will be happening with no moonlight - it's much better viewing," Dr Jacob said.

"It's also the weekend so people can stay up late, even into the early hours," he said.

The Piscis Austrinids will likely peak first tonight on July 28, while the Southern Delta Aquariids and the Alpha Capricornids will peak on July 30.

What is a meteor shower?

Meteor showers are the Earth passing through dust trails left behind by comets, said Associate Professor Nicholas Jones from the University of Wollongong.

"Mostly at night-time, you see the odd random meteor occurring here or there, but what astronomers are really interested in is showers, when you see a few more than usual," Professor Jones said.

The Delta Aquariids, peaking on July 30, is from the Machholz comet, he said.

"Sometimes the comets are periodic and come back, and some you never see again."

Meteorites, the debris flying through space, are surprisingly small but travel at incredible speeds.

"They're travelling faster than a speeding bullet," Professor Jones said.

How do I watch them?

To get the best view of the meteor showers, Dr Jacob said viewers should try to find a spot outside of the city without much light.

The best time to view the showers is after 11pm, and you'll likely see more meteors after midnight due to the Earth's movements and the direction of the showers.

"It's like rain on a car; you seem to see more rain on the front windscreen than on the back window," Dr Jacob said.

"If you're on the part of the earth moving into the direction of the shower, you'll see more meteors."

The best viewing nights will be dependent on how clear the skies are over Friday and the weekend, he said.

What will you see?

Meteors look like streaks of light, Dr Jacob said, and they're interchangeable with the word 'shooting star'.

The three showers are quite close together and will appear to radiate from a similar part of the sky, he said, so there may be some confusion.

The Southern Delta Aquariids will give us more meteoroids per hour, but the Alpha Capricornids will have the brightest meteors.

"Most of the meteors you'll see in this region will be from the Delta Aquariids," he said.

"However, the Alpha Capricornids occasionally have very bright meteors, called fireballs."

While a bright meteorite might be the size of a grain of rice, a fireball can be as bright as the planet Venus and the size of a walnut to a cricket ball, he said.

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Where do I look?

Meteor showers are named after the stars or constellations they appear to radiate from, and this point changes throughout the evening as the Earth moves.

"If you're driving in snow, the snow seems to come from a single point in front of you," Dr Jacob said.

"The same effect happens when you're looking at a meteor shower."

In the early evening, stargazers should look to the east or northeast.

By midnight, shift to looking to the north, and as dawn approaches, look west or northwest.