A comet is an icy, small Solar System body that warms and begins to release gases when passing close to the Sun. This produces an extended, gravitationally unbound atmosphere or coma surrounding the nucleus, and sometimes a tail of gas and dust gas blown out from the coma. These phenomena are due to the effects of solar radiation and the outstreaming solar wind plasma acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth’s diameter, while the tail may stretch beyond one astronomical unit. If sufficiently close and bright, a comet may be seen from Earth without the aid of a telescope and can subtend an arc of up to 30° (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures and religions.
Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star. Long-period comets are set in motion towards the Sun by gravitational perturbations from passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space.
Comet C/2022_E3 (ZTF)
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km), and the closest approach to Earth will be on 1 February 2023, at a distance of 0.28 AU (42 million km). The comet exceeded magnitude 6 and is dimly visible with the naked eye.
Photographed with APO107 refractor telescope and ASI 2600MC color camera in Åva, February 2023. 60*20s exposure with IDAS HEUIB filter and postprocessed in Pixinsight with Comet align function.
Comet C/2022_E3 (ZTF)
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km), and the closest approach to Earth will be on 1 February 2023, at a distance of 0.28 AU (42 million km). The comet exceeded magnitude 6 and is dimly visible with the naked eye.
Photographed with RC8 reflector telescope and ASI 2600MC color camera in Stuvsta, February 2023. 24*30s exposure with IDAS LPS D2 light pollution filter and postprocessed in Pixinsight with Comet align function.
Comet C/2022_E3 (ZTF)
C/2022 E3 (ZTF) is a long period comet from the Oort cloud that was discovered by the Zwicky Transient Facility on 2 March 2022. The comet has a bright green glow around its nucleus which is due to the effect of sunlight on its molecules, especially diatomic carbon and cyanogen.
The comet reached its perihelion on 12 January 2023, at a distance of 1.11 AU (166 million km), and the closest approach to Earth will be on 1 February 2023, at a distance of 0.28 AU (42 million km). The comet exceeded magnitude 6 and is dimly visible with the naked eye.
Photographed with RC8 reflector telescope and ASI 2600MC color camera in Stuvsta, February 2023. 24*30s exposure with IDAS LPS D2 light pollution filter and postprocessed in Pixinsight with Comet align function – Comet is point of registration.
The comet 46P Wirtanen in the constellation Lynx
46P Wirtanen is a so-called short-period comet that returns every 5.4 years. It moves out to Jupiter in an elliptical orbit which then takes it past the Earth towards the Sun. The chunk of ice is estimated to have a diameter of about 1.2 km, but passed us this time on December 16, 2018 at a distance of about 10 million km, so we escaped the same fate as the dinosaurs (this time – you never know what Jupiter does to the orbits of these comets).
Photographed with 85mm lens on the Nikon D800 DSLR camera in Åva, December 2018. 33 exposures of 1 minute each.
The comet 46P Wirtanen in the constellation Lynx
46P Wirtanen is a so-called short-period comet that returns every 5.4 years. It moves out to Jupiter in an elliptical orbit which then takes it past the Earth towards the Sun. The chunk of ice is estimated to have a diameter of about 1.2 km, but passed us this time on December 16, 2018 at a distance of about 10 million km, so we escaped the same fate as the dinosaurs (this time – you never know what Jupiter does to the orbits of these comets).
Photographed with 35mm lens on the Nikon D800 DSLR camera in Åva, December 2018. 15 exposures of 1 minute each.
The comet 41P/Tuttle_Giacobini-Kresak
The comet 41P/TGK is a periodic comet with a period of 5.4 years and an average distance to the Sun of 3.1 AU. Here the comet is at RA 11h 15m and Dec +55 degrees, i.e. at the edge of the constellation the Big Dipper.
Photographed with APO107 refractor telescope and Atik 360EX monochrome camera in Åva, march 2017. 3*4 min exposure with monochrome camera for the stars and 3*5 min exposure of the comet. Aligned with Comet Align and combined with the star background.
The comet C/2013 US10 (Catalina)
Aperiodical comet passing the Sun on November 15th 2015 and here leaving the solar system again. The distance is about 2 astronomical units (AU) from the Earth and magnitude about +9.
Photographed with CPC925 reflector telescope and Nikon D800 camera in Åva, March 2016. Exposure was 12*90s.
Comet 103P/Hartley
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.48 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be 1.2 to 1.6 kilometres.
Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within 700 kilometers of Hartley 2 as part of its extended mission. As of November 2010 Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005.
Photographed with 85mm lens and Nikon D800 DSLR on Astrotracker in Åva, September 2023. Exposure was 17 min at ISO 800.
Comet 103P/Hartley
Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.48 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be 1.2 to 1.6 kilometres.
Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within 700 kilometers of Hartley 2 as part of its extended mission. As of November 2010 Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005.
Photographed with 85mm lens and Nikon D800 DSLR on Astrotracker in Åva, September 2023. Exposure was 17 min at ISO 800.
