Showing posts with label Comets. Show all posts
Showing posts with label Comets. Show all posts

Tuesday, 23 June 2026

The June Bootid Meteor Shower.

The June Bootid Meteor Shower is visible each year between 26 June and 2 July, typically peaking on 27 June. This meteor shower if highly unpredictable in nature, with most years producing very few meteors, but the shower occasionally having peak years, in which hundreds of meteors are visible each hour; the most recent major peak year happened in 1998 (a smaller peak was recorded in 2004), with the three peaks prior to that happening in 1927, 1921, and 1916. The shower has a radiant point (point from which the meteors appear to radiate) in the constellation of Boötes, close to the North Pole, making the shower possible to spot from anywhere in the Northern Hemisphere, but hard to see in the Southern Hemisphere. Unfortunately, this year's peak activity comes only two days before the Full Moon on 29 June, which means that good observation of the meteors may be hampered by the brightness of the Moon.


The radiant point of the June Bootid Meteor Shower. Space Weather.

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 June Bootids Meteor Shower is caused by the Earth passing through the trail of comet 7P/Pons-Winnecke, 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. 7P/Pons-Winnecke visits the Inner Solar System every 6.37 years, most recently in May 2021, and last came close to the Earth in 1939.

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

7P/Pons-Winnecke was discovered on 12 June 1819 by French astronomer Jean-Louis Pons, then based at Marseilles Observatory, and rediscovered by Friedrich August Theodor Winnecke at Pulkovo Observatory near Saint Petersburg. The designation 7P/Pons-Winnecke implies that it was the seventh comet discovered (7/ - 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), and that it was discovered by Pons and Winnecke.

7P/Pons-Winnecke immaged on 23 September 2015 from Kiev, Ukraine. The image is a single 300 second exposure, with the slightly elongate objects being stars that have moved over the course of the exposure. Alexander Baransky/Kiev Comet Station/Fachgruppe Kometen.

Comet 7P/Pons-Winnecke currently completes one orbit every 2326 days (6.37 years) on an eccentric orbit tilted at 22.3° to the plane of the Solar System, that takes it from 1.26 AU from the Sun (126% of the average distance at which the Earth orbits the Sun) to 5.61 AU from the Sun (5.61 times as far from the Sun as the Earth, and slightly outside the orbit of Jupiter). As a comet with a period of less than 20 years with an orbit angled at less than 30° to the plane of the Solar System, 7P/Pons-Winnecke is considered to be a Jupiter Family Comet.

The orbit and current position of 7P/Pons-Winnecke. JPL Small Body Database.

This orbit means that 7P/Pons-Winnecke occasionally comes close to the Earth, with the last close approach having happened on 1 July 1939, when it reached a distance of 0.11 AU from the Earth (11% of the distance between the Earth and the Sun, or 16 052 000 km). The comet will next come close to us in June 2062, when it will reach a distance of 0.17 AU from the Earth.

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Saturday, 13 June 2026

Comet C/2023 R1 (PANSTARRS) makes its closest approach to Earth.

Comet C/2023 R1 (PANSTARRS) will make its closest approach to the Earth today (Saturday 13 June 2026), when it will reach a distance of 2.63 AU (i.e 2.63 times the average distance between the Earth and the Sun), or 392 873 130 km from us. At this time it will be in the constellation of Ophiuchus, and have an apparent optical magnitude of 12, meaning it will be hard to spot without a fairly good telescope to observe it. Nevertheless, this closest approach falls the day before the New Moon on 14 June, so observers with appropriate equipment may be able to see it in the late evening (the comet will set before midnight).

The approximate positions and orbits of the C/2023 R1 (PANSTARRS), the Earth, and the planets of the Inner Solar System on 13 June 2026. Gideon van Buitenen.

Comet C/2023 R1 (PANSTARRS) was discovered on 7 September 2023 by the PANSTARRS sky survey, located at Haleakala Observatory, Hawaii. The name C/2023 R1 (PANSTARRS) implies that it is a Comet (C/), that it was the 1st comet (1) discovered in the first half of September 2021 (period 2023 R), and that it was discovered by the PANSTARRS sky survey.

Image of C/2023 R1 (PANSTARRS) taken on 25 July 2025. The comet is the point between the yellow cross hairs, the elongate objects are stars, with the elongation being caused by the tracking of the comet over the length of the exposure. Toshihiko Ikemura/Hirohisa Sato/Seiichi Yoshida.

Comet C/2023 R1 (PANSTARRS) is a Parabolic Comet, which is to say a comet that was disrupted from an orbit in the Oort Cloud, and is passing through the Inner Solar System on a parabolic orbit that will probably not bring it back again. This parabolic trajectory is tilted at an angle of 149.3° to the plain of the Solar System.

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Monday, 4 May 2026

The Eta Aquariid Meteor Shower.

The Eta Aquariid Meteor Shower will peak before dawn on Wednesday 6 May 2026, with up to 45 meteors per hour at it's peak, radiating from the constellation of Aquarius. The radiant point of this shower does not spend long above the horizon in the Northern Hemisphere at this time of year, but is often a good display in the Southern Hemisphere between midnight and dawn. The Eta Aquarids are potentially visible between 19 April and 28 May, but are extremely hard to spot away from the peak of activity. With the last Quarter Moon in Sagittarius, pre-dawn viewing may suffer from some light interference. 

The radiant point (point from which the meteors appear to radiate) of the Eta Aquariid Meteors. Universe Today.

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) 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 Eta Aquarid Meteor  Shower is caused by the Earth passing through the trail of Halley's Comet, 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. Halley's Comet only visits the inner Solar System every 75 years (most recently in 1986 and next in 2061), but the trail of particles shed by it forms a constant flow, which the Earth crosses twice each year; in May when it causes the Eta Aquarid Meteor Shower and in October when it causes the Orionid Meteor Shower.

Halley's Comet imaged on 8 March 1986 from Easter Island. William Liller/International Halley Watch Large Scale Phenomena Network/NASA/Wikimedia Commons.

Halley's Comet has been observed repeatedly and recognised as the same recurring object since at least 240 BC. However, it takes its modern name from the eighteenth century English Astronomer Edmund Halley, who determined the comet's periodicity in 1705.

Halley's Comet completes one orbit every 75.32 years (27 509 days) on an eccentric, orbit tilted at 162° to the plane of the Solar System (i.e. a retrograde orbit, at an angle of18° to the plane of the Solar System, but travelling in the opposite direction to the majority of the objects in the Solar System), that takes it from 0.56 AU from the Sun (59% of the average distance at which the Earth orbits the Sun, and inside the orbit of the planet Venus) to 35.1 AU from the Sun (35.1 times as far from the Sun as the Earth, and outside the orbit of the planet Neptune). As a comet with a period of more than 20 years but less than 200 years, Halley's Comet is considered to be a Periodic Comet, and a Halley-type Commet.

The orbit of Halley's Comet. Nagual Design/Wikimedia Commons.

Halley's Comet was visited by the European Space Agency's Giotto Probe in and Russian Vega 1 and Vega 2 probes March 1986, which were able to determine that the nucleus of the comet was only 15 km across, although it was surrounded by a coma about 100 000 km in diameter, made up of fragments of dust and ice released from the surface as it was heated by the Sun, causing the ices on its surface to sublimate (turn directly from solids to gasses), and that this material comprised 80% water, 10% carbon monoxide, 2.5% methane and ammonia, as well as trace amounts of more complex hydrocarbons, iron and sodium.

Halley's Comet imaged by the Giotto Probe on 14 March 1986. European Space Agency/Wikimedia Commons.

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Tuesday, 21 April 2026

The Lyrid Meteor Shower.

The Lyrid Meteor Shower is expected to be visible between Thursday 16 and Saturday 25 April this year (2022), and will be at peak visibility on Wednesday 22 April. With the First Quarter Moon not falling till the 24th this year,  there should be a good chance to see some meteors in cloudless areas. At its peak the Lyrid Meteor shower typically produces about 20 meteors per hour, though higher rates have been recorded. The Lyrid Meteors take their name from the constellation of Lyra, from which they appear to radiate, at a point close to the star Vega, which will be above the horizon for most of the night from most places in the Northern Hemisphere, while rising at about midnight in much of the Southern Hemisphere. Viewing is typically best in the hours before dawn, although peak meteor activity should occur at about 8.00 pm GMT.

The Radiant Point (i.e. point from which the meteors appear to radiate) of the Lyrid Meteors. Bruce McClure/Joni Hall/EarthSky/Wikimedia Commons.

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 Lyrid Meteors are comprised of debris from the comet C/1861 G1 Thatcher (named after its discoverer, the astronomer A. E. Thatcher, not the politician). This is a long-period comet that spends most of its time in the Oort Cloud, only visiting the inner Solar System once every 415 years, the last occasion being in 1861. When the comet visits the inner Solar System it is heated by the Sun, melting the ices that make up its surface and releasing a trail of dust, which continues to follow the path of the comet. The Earth passes through this trail in April each year, creating a light show as the dust particles burn in the upper atmosphere.

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

Comet C/1861 G1 Thatcher completes one orbit every 415 years on an eccentric orbit tilted at 79.8° to the plane of the Solar System, that takes it from 0.92 AU from the Sun (92% of the average distance at which the Earth orbits the Sun) to 106 AU from the Sun (110 times as far from the Sun as the Earth, and more than three times the distance at which the planet Neptune orbits the Sun). The comet last visited the Inner Solar System in 1891, and is expected to return again in 2306. As a comet with an orbital period of more than 200 years it is considered to be a Long Period Comet.

The orbit and current position of Comet C/1861 G1 Thatcher. JPL Small Body Database.

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