The Perseid Meteor Shower.

The Perseid Meteor Shower lasts from late July to early September each year, and are expected to be at a peak before dawn on Tuesday 12 August 2025. Viewing will be less than ideal for the Perseids this year, as the meteors peak after the Full Moon on Saturday 9 August. The Perseids get their name from the constellation of Perseus, in which the meteors have their radiant (the point from which they appear to originate). Potentially, at the peak of activity, the Perseid Meteor Shower can produce over 150 meteors per hour, although it is best seen from the Northern Hemisphere, as the constellation of Perseus is near to the North Pole. 

The radiant point for the Perseid Meteor Shower. N Sanu/Wikimedia Commons.

Meteor showers are thought to be largely composed of material from the tails of comets. Comets are composed largely of ice (mostly water and carbon dioxide), and when they fall into the inner Solar System the outer layers of this boil away, forming a visible tail (which always points away from the Sun, not in the direction the comet is coming from, as our Earth-bound experience would lead us to expect). Particles of rock and dust from within the comet are freed by this melting (strictly sublimation, transforming directly from a solid to a gas due to the low pressure on it's surface) of the comet into the tail and continue to orbit in the same path as the comet, falling behind over time.

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

The Perseid Meteors are caused by the Earth passing through the trail of the Comet 109P/Swift-Tuttle, and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process.

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

Comet 109P/Swift-Tuttle was discovered independently in July 1862 by the astronomers Lewis Swift and Horace Parnell Tuttle, after whom it is named. The number 109P implies that it was the 109th comet discovered (strictly speaking people had been observing comets for thousands of years, but it was not until the mid-eighteenth century that it was realised that they were predictable objects that returned cyclically), that it is a periodic comet (P - again, most comets are periodic, but the term 'periodic comet' is reserved for those with periods of less than 200 years, since these can be reliably predicted).

Comet 109P/Swift-Tuttle imaged in 1992 during its last visit to the Inner Solar System. The Planetary Society/NASA.

Comet 109P/Swift-Tuttle itself only visits the Inner Solar System once every 133 years, last doing so in 1992, on an eccentric orbit tilted at 113° to the plane of the Solar System (or 67° with a retrograde orbit - an orbit in the opposite direction to the planets - depending on how you look at it), that takes it from 0.95 AU from the Sun (95% of the distance at which the Earth orbits the Sun) to 51.22 AU from the Sun (51.22 times as far from the Sun as the Earth, more than three times as far from the Sun as Neptune and slightly outside the Kuiper Belt, but only scraping the innermost zone of the Oort Cloud). 

The orbit and current position of Comet 109P/Swift Tuttle. JPL Small Body Database Browser.

109P/Swift-Tuttle is next expected to visit the Inner Solar System in 2126, reaching about 22 950 00 km (0.15 AU) from Earth in August of that year. As a comet with a period of more than 20 years but less than 200 years, 109P/Swift-Tuttle is considered to be a Periodic Comet, and a Halley-type Comet.

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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 30 July this year, producing up to 25 meteors per hour. Best viewing this year is predicted to be between 2.00-3.00 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 Aquari (hence the name) will be highest in the sky. This year the peak of activity will fall slightly before the first quarter moon on 1 August, and the Moon will be in the constellation of Virgo, making it reasonably distant from Delta Aqaurius in the sky, and setting before midnight, so that it should not interfere with viewing of the peak of the meteor shower.

The radiant point of the Delta Aquariid Meteors. David Dickinson/Starry Night/Universe Today.

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, 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 was discovered by amateur astronomer Donald Machholz from Loma Peak in California; the name 96P/Machholz implies that it was 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). 

The orbit and current position of Comet 96P/Machholz. JPL Small Body Database.

96P/Machholz has an orbital period of 1929 days (5.28 years) and a highly eccentric orbit tilted at an angle of 58.5° 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 5.94 AU from the Sun at aphelion (5.94 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 is considered to be a Jupiter Family Comet.

Image of 96P/Machholz close to the sun taken by the Solar and Heliospheric Observatory on 8 January 2002. NASA/ESA/Solar and Heliospheric Observatory.

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3I/Atlas: Third interstellar comet discovered.

On Tuesday 1 July 2025 scientists at the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope in Río Hurtado, Chile, observed a body 4.53 AU from the Sun (i.e. 4.53 times as far from the Sun as the planet Earth) between the constellations of Serpens Cauda and Sagittarius, which was given the provisional designation A11pl3Z. This object was travelling towards the Inner Solar System at a speed of 65 km per second, on what appeared to be a more-or-less straight trajectory, highly unusual in a body orbiting the Sun.

Discovery images for object A11pl3Z. ATLAS/University of Hawaii/NASA/Wikipedia.

A series of follow-up observations  by both professional and amateur astronomers confirmed that the body was a comet on a hyperbolic trajectory (a trajectory which will take it straight through the Solar System and out into interstellar space. Most such parabolic comets derive from the Oort Cloud, a vast disc of thinly spread cometary bodies between 2000 and 200 000 from the Sun. These comets are knocked from their orbits be close encounters with other bodies, plunge through the Inner Solar System once, then vanish into the depths of space. However, two previous comets have been found to be on trajectories which cannot be explained in this way, these being 1I/‘Oumuamua and 2I/Borisov, and on Tuesday 2 July it was confirmed that A11pl3Z was a third such body, leading to it being given the designation 3I/Atlas, in which the 'I' stands for 'Interstellar body', the '3' indicates that it was the third such body discovered, and 'ATLAS' refers to the ATLAS asteroid impact early warning system, which discovered the object.

The trajectory and current position (on 5 July 2025) of interstellar comet 3I/ATLAS. The Sky Live.

3I/ATLAS is predicted to reach its perihelion (closest point on its trajectory to the Sun) on 29 October 2025, when it will be 1.36 AU from the Sun. It will make its closet approach to the Earth on 19 December, when it will be 1.80 AU from us. Unfortunately, these events will happen while the comet is on the far side of the Sun, preventing observations during this period. The comet will pass the planet Mars at a distance of 0.19 AU on 3 October, and Jupiter at 0.38 AU on 16 March 2026. 3I/ATLAS is apparently a weekly active comet with an absolute magnitude of about 12 (a measure of its brightness), which implies a nucleus with a diameter of 3-5 km.

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The Daytime Arietid Meteor Shower.

The Arietid Meteor Shower lasts from mid April till late June each year, and is expected to peak before dawn on Tuesday 10 June this year, and originating (appearing to come from) the constellation of Aries. Meteors from this shower can be very bright, leading to the label 'Daytime' Meteors (i.e. meteors that can be seen during the day), although the majority are quite dim, and can be hard to spot. At its peak, the shower can produce about 50 meteors per hour. This year that peak will coincide with the Full Moon, so viewing may be less than optimal.

The origin point for the Aried Meteors seen from the Northern Hemisphere in early June. Spaceweather.

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 origin of the Arietid Meteors is unclear. No body has been confidently identified as the source of the Arietid Meteors, though both the asteroid 1566 Icarus and the comet 96P/Machholz have been suggested. 

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

Though the Arietid Meteors can be hard to see, it may be possible to 'hear' them using an FM radio. In order to do this it will be necessary to find a frequency between 88.0 and 108.0 MHz without any transmissions or significant static (this may not be possible in urban areas). Meteors passing though the atmosphere generate radio waves at these frequencies, which can be heard as 'bumps' or 'chirps'. More detailed observations can be used if the radio set-up has a directional antenna, allowing the observer to concentrate on a particular part of the sky (this is essentially what a radio telescope is).

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The Ursid Meteor Shower.

The Ursid Meteors are expected to peak at about 10 pm GMT on the evening of Sunday 22 December this year, with the shower being potentially visible to some extent between Sunday 17 and Monday 26 December.  The shower is typically best seen between midnight and dawn from anywhere in the Northern Hemisphere (it is difficult,if not impossible, to view it from the Southern Hemisphere). The extent of the shower is variable, some years producing over 100 meteors per hour at its peak, others less than 10. The peak of this years shower coicides with the Third Quarter Moon, also on 22 December, so viewing may be somewhat impaired, as glare from the Moon can hinder the viewing of meteors. The meteor shower gets its name from the constellation of Ursa Minor, in which it appears to originate.

The radiant (apparent point of origin) of the Ursid Meteors. BBC Science Focus Magazine/PA.

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 Ursid Meteor Shower is caused by the Earth passing through the tail of Comet 8P/Tuttle, and encountering dust from the tail of this comet. The dust particles strike the atmosphere at speeds of over 200 000 km per hour, burning up in the upper atmosphere and producing a light show in the process. The Earth does not need to pass close to Comet 8P/Tuttle for the meteor shower to occur, it simply passes through a trail of dust from the comet's tail that is following the same orbital path. Comet 8P/Tuttle visits the Inner Solar System once every 13.6 years, last doing so in 2021.

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

Comet 8P/Tuttle was discovered by Horace Parnell Tuttle on 5 January 1858. The designation 8P/Tuttle indicates that it was the eighth comet discovered (people have known about comets for thousands of years, but it was only realised that they were objects orbiting the Sun, which could be repeatedly observed and predicted, in the mid-eighteenth century), that it is a Periodic Comet (comet with an orbital period of less than 200 years) and that it was discovered by Horace Parnell Tuttle.

Comet 8P/Tuttle imaged from Weißenkirchen in der Wachau in Austria on 30 December 2007. Michael Jäger/Spaceweather.

Comet 8P/Tuttle has an orbital period of 4972 days (13.6 years) and a highly eccentric orbit tilted at an angle of 55.0° to the plain of the Solar System, that brings it from 1.03 AU from the Sun at closest perihelion (103% of the distance between the Earth and the Sun) to 10.4 AU from the Sun at aphelion (10.4 times as far from the Sun as the Earth or slightly outside the orbit of the planet Saturn). As a comet with a period of less than 20 years, 8P/Tuttle is considered to be a Jupiter Family Comet.

The calculated orbit and position on 21 December 2024 of 8P/Tuttle.  JPL Small Body Database.

This means that 8P/Tuttle has occasional close encounters with the Earth, with the last thought to have happened in January 2008 and the next predicted in December 2048. The comet also has occasional close encounters with the planets Jupiter, which it last came close to in December 1995 and is next predicted to pass in September 2078, and Saturn, which it last came close to in February 1930 and is expected to pass again in February 2107. Objects which make close passes to multiple planets are considered to be in unstable orbits, and are often eventually knocked out of these orbits by these encounters, either being knocked onto a new, more stable orbit, dropped into the Sun, knocked out of the Solar System or occasionally colliding with a planet. 

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