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Algol eclipse dates and times for January 2023
Algol (β Per) is a bright eclipsing binary system located in the northern constellation of Perseus and one of the best-known variable stars in the sky. Often referred to as the "Demon Star", most of the time it shines at mag. +2.1 but every two days, 20 hours and 49 minutes it suddenly dips in brightness to mag. +3.4, remaining dim for about 10 hours before returning to its original state.
Why the brightness change. The Algol system consists of at least three-stars (β Per A, β Per B and β Per C) with the orbital plane of Algol A and B directly in line with the Earth. The regular dips in brightness occur when the dimmer B star moves in front of and eclipses the brighter A star. There is also an extra dimension in that a secondary eclipse occurs when the brighter star occults the fainter secondary, resulting in a very small dip in brightness that can be detected with photo-electrical equipment.
Algol eclipse dates and times for February 2023
Algol (β Per) is a bright eclipsing binary system located in the northern constellation of Perseus and one of the best-known variable stars in the sky. Often referred to as the "Demon Star", most of the time it shines at mag. +2.1 but every two days, 20 hours and 49 minutes it suddenly dips in brightness to mag. +3.4, remaining dim for about 10 hours before returning to its original state.
Why the brightness change. The Algol system consists of at least three-stars (β Per A, β Per B and β Per C) with the orbital plane of Algol A and B directly in line with the Earth. The regular dips in brightness occur when the dimmer B star moves in front of and eclipses the brighter A star. There is also an extra dimension in that a secondary eclipse occurs when the brighter star occults the fainter secondary, resulting in a very small dip in brightness that can be detected with photo-electrical equipment.
Sirius - Alpha Canis Majoris - α CMa
There are at least 6,000 stars bright enough to be visible with the naked eye. Under dark skies, up to about 3,000 can be seen at any one time (since one half of the Earth is in daylight). However, none can rival the brilliance of Sirius, the brightest night time star.
Located in the constellation of Canis Major, Sirius shines with an apparent magnitude of -1.46. It's noticeably brighter than its nearest rival Canopus (α Car mag. -0.72) and four times more brilliant than Arcturus, the brightest star in the northern section of sky. Sirius is also known as the "Dog Star". When close to the horizon it twinkles. Of course, the colour variations are only a result of the Earth's unsteady atmosphere. In practice, all stars do twinkle and to a lesser extent the planets as well.
To the naked eye Sirius appears as a single star, but it's actually a binary system. The primary component is a white main sequence star of spectral type, A1V, named Sirius A. This star is the one visible to the naked eye. It has a radius of 1.7 times that of the Sun and is 25 times more luminous.
Algol eclipse dates and times for November 2022
Algol (β Per) is a bright eclipsing binary system located in the northern constellation of Perseus and one of the best-known variable stars in the sky. Often referred to as the "Demon Star", most of the time it shines at mag. +2.1 but every two days, 20 hours and 49 minutes it suddenly dips in brightness to mag. +3.4, remaining dim for about 10 hours before returning to its original state.
Why the brightness change. The Algol system consists of at least three-stars (β Per A, β Per B and β Per C) with the orbital plane of Algol A and B directly in line with the Earth. The regular dips in brightness occur when the dimmer B star moves in front of and eclipses the brighter A star. There is also an extra dimension in that a secondary eclipse occurs when the brighter star occults the fainter secondary, resulting in a very small dip in brightness that can be detected with photo-electrical equipment.
Algol eclipse dates and times for December 2022
Algol (β Per) is a bright eclipsing binary system located in the northern constellation of Perseus and one of the best-known variable stars in the sky. Often referred to as the "Demon Star", most of the time it shines at mag. +2.1 but every two days, 20 hours and 49 minutes it suddenly dips in brightness to mag. +3.4, remaining dim for about 10 hours before returning to its original state.
Why the brightness change. The Algol system consists of at least three-stars (β Per A, β Per B and β Per C) with the orbital plane of Algol A and B directly in line with the Earth. The regular dips in brightness occur when the dimmer B star moves in front of and eclipses the brighter A star. There is also an extra dimension in that a secondary eclipse occurs when the brighter star occults the fainter secondary, resulting in a very small dip in brightness that can be detected with photo-electrical equipment.
Orion - Constellation Guide
Orion
Orionis
Ori
The Hunter
Introduction
Orion is a prominent constellation that's one of the brightest and most familiar sights in the night sky. Straddling the celestial equator it can be seen from all locations on Earth. Named after a great hunter in Greek mythology, it contains two first magnitude stars, many other bright stars, a famous belt, spectacular nebulae, some impressive multiple stars and fine open clusters. Its most famous inhabitant, the Orion Nebula, is one of the most spectacular deep sky objects in the sky.
The distinctive pattern of Orion has been used historically and in the modern World extensively. The earliest linking is an ivory carving found in a cave in the Ach valley in Germany, which is estimated to be at least 32,000 years old. In Greek mythology, Orion was a handsome strong hunter, born to Euryale the daughter of King Minos of Crete and Poseidon, the god of the sea. Many myths surround the character particularly involving his death. Various versions exist, but generally Orion brought the wrath of goddess Artemis who sent the scorpion to kill him. The resulting outcome is that the hunter and the scorpion are placed on opposite sides of the sky. When Scorpius rises in the east, Orion is setting in the west.
In medieval Muslim astronomy, Orion was known as al-jabbar, the giant. In old Hungarian tradition, Orion was a magic Archer or Reaper and in China the constellation was one of the 28 lunar mansions that reflect the movement of the Moon. The Egyptians associated Orion with Osiris, the god of death, afterlife, resurrection, regeneration and rebirth. They also aligned part of the Great Pyramid of Giza with Alnitak, one of the stars of the belt. For the Aztecs, Orion rising in the east signaled the time to perform the "New Fire" ceremony, a ritual designed to postpone the end of the World. More recently, the film company Orion Pictures used the constellation's main shape as its logo.
Orion is best seen during the months of December, January and February.
Betelgeuse - Alpha Orionis - α Ori
Betelgeuse is a red supergiant in Orion that's one of the most famous stars in the sky. It's an irregular variable that usually fluctuates between magnitudes +0.3 and +0.8, though on rare occasions it has been known to peak at magnitude 0.0 and dim down to magnitude +1.2. The star currently hovers around magnitude +0.42. It marks the upper left-hand corner of the ancient hunter figure.
Although lettered alpha (α) Orionis, Betelgeuse is usually fainter than Rigel (β Orionis - mag. +0.13) and is therefore the constellations second brightest star. Sir John Herschel, in 1836, was the first person to record brightness variations and on two occasions, in October 1837 and November 1839, he observed it to be brighter than Rigel. At best, Betelgeuse is comparable in brightness to Rigel and Capella (α Aur - mag. +0.08) but when towards the lower end of its range, appears more like Aldebaran (α Tau - mag(v). +0.75 -> +0.85).
Messier 42 - M42 - The Great Orion Nebula (Emission/Reflection)
M42, also known as the Great Orion Nebula or Orion Nebula, is the prime deep sky attraction in the constellation of Orion and a showpiece deep sky object. With an apparent magnitude of +4.0, it's easily visible to the naked eye. This emission / reflection nebula and star forming region spans more than a degree of sky and is therefore one of the largest and brightest objects of its type.
Orion is a prominent constellation and one of the most recognizable and familiar sights. Located on the celestial equator, it's visible throughout the World and best seen during the months of December, January and February. The constellation is filled with bright stars, including first magnitude Rigel and Betelgeuse plus a further five second magnitude stars. Three of the second magnitude stars (Mintaka, Alnilam and Alnitak) form the famous belt of Orion. Positioned just 5 degrees south of the belt is the Orion Nebula itself, which is part of the Hunters Sword.
Messier 45 - M45 - The Pleiades (Open Cluster)
M45, commonly known as the Pleiades or Seven Sisters, is the finest open cluster in the sky. It's a breathtaking site, known since antiquity and easily visible to the naked eye. Located in the large and prominent zodiac constellation of Taurus, this showpiece object is best seen during the Northern Hemisphere Winter and the Southern Hemisphere Summer months.
Finding M45 is easy. The cluster is positioned about 14 degrees northwest of orange giant star Aldebaran (mag. +0.9), the brightest star in Taurus. At first glance with the naked eye, it's obvious that something is special about this small section of sky. On closer inspection, M45 reveals itself to be a beautiful cluster of about half a dozen white stars, covering an area much greater than that of the full Moon. At the heart of the cluster is a set of stars that form a small dipper shape, similar to the brightest stars of Ursa Major. Even under light polluted skies the dipper shape is readily visible. From dark sites, the Pleiades is an outstanding naked eye object. The main stars appear bright and striking, with up to 10 or more visible under ideal conditions.
