The Southern Delta Aquariid Meteor Shower.

The Southern Delta Aquariid Meteor Shower is visible between roughly 12 July and 23 August each year, and is expected to peak on Tuesday 30 July this year, producing up to 25 meteors per hour. Best viewing this year is predicted to be between 3.00 am (this will be in local time wherever they are viewed from, as the time reflects the orientation of the planet to the rest of the Solar System) and dawn, when the radiant point of the shower (point from which the meteors appear to radiate), which is close to the star Delta Aquarii (hence the name) will be highest in the sky. This year the peak of activity will fall a few days before the new moon on 4 August, and the Moon will be in the constellation of Taurus, rising slightly after midnight on 30 July, so light interference should be minimal.

The radiant point of the Southern Delta Aquariid Meteor Shower. EarthSky.

Meteor streams are thought to come from dust shed by comets as they come close to the Sun and their icy surfaces begin to evaporate away. Although the dust is separated from the comet, it continues to orbit the Sun on roughly the same orbital path, creating a visible meteor shower when the Earth crosses that path, and flecks of dust burn in the upper atmosphere, due to friction with the atmosphere.

The Earth passing through a stream of comet dust, resulting in a meteor shower. Not to scale. Astro Bob.

The Southern Delta Aquariids are thought to be caused by the Earth passing through the trail of Comet 96P/Machholz 1, where it encounters thousands of tiny dust particles shed from the comet as its icy surface is melted (strictly sublimated) by the heat of the Sun. 96P/Machholz is a short period, Jupiter Family Comet, crossing our orbit every 5.24 years, but the trail of particles shed by it forms a constant flow.

How the passage of the Earth through a meteor shower creates a radiant point from which they can be observed. In The Sky.

96P/Machholz 1 was discovered by amateur astronomer Donald Machholz from Loma Peak in California on 12 May 1996. The name 96P/Machholz implies that it was the first comet discovered by Machholz and was the 96th periodic comet discovered (a periodic comet is a comet which orbits the Sun in less than 200 years). 

Comet 96P/Machholz 1 imaged on 4 April 2007 by the SECCHI inner Heliospheric Imager on the STEREO Ahead space-based observatory. NASA/Wikimedia Commons.

96P/Machholz1 has an orbital period of 1931 days (5.29 years) and a highly eccentric orbit tilted at an angle of 58.1° to the plain of the Solar System, that brings it from 0.12 AU from the Sun at perihelion (12% of the distance between the Earth and the Sun, considerably inside  the orbit of Mercury, and closer to the Sun than any other known periodic comet); to 5.95 AU from the Sun at aphelion (5.96 times as far from the Sun as the Earth or slightly more than the distance at which Jupiter orbits). As a comet with a period of less than 20 years, 96P/Machholz 1 is considered to be a Jupiter Family Comet.

The orbit and position of 96P/Machholz 1 on 30 July 2024. JPL Small Body Database.

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