Alioth has a mass of 2. It shines with solar luminosities with an effective temperature of about 9, K. Alioth is a peculiar star, one that shows variations in its spectral lines over a period of 5. It is classified as an Alpha 2 Canum Venaticorum variable. It is the brightest of the seven stars in the Big Dipper asterism. It has an apparent magnitude of 3. Megrez is a white main sequence star of the spectral type A3 V.
It has a mass of 1. With a surface temperature of about 9, K, it is 14 times more luminous than the Sun. Like its Big Dipper neighbours, it is believed to be about million years old. The star has a mass 2. It is Phecda has an astrometric binary companion, an orange dwarf of the spectral type K2 V that perturbs it and causes it to wobble around the centre of mass.
The two stars have an orbital period of The companion has a mass of 0. It shines with only 0. It is the second brightest star in Ursa Major. Dubhe is an orange giant with the stellar classification of K0III. It is a spectroscopic binary star, with a white main sequence companion of the spectral type F0V.
The two stars are 23 astronomical units apart and have an orbital period of Dubhe is 4. It is a slow spinner, with a projected rotational velocity of 2. The companion is less massive, with about 1. It has a visual magnitude of 4. It is classified as a suspected variable. The star has a mass of 2. With a surface temperature of 9, K, it is Following a line further leads to Spica , the 17 th brightest star in the night sky, and the brightest star in the zodiacal constellation of Virgo.
Two of the stars marking the cup of the Big Dipper lead the way to Polaris , the current North Pole Star, which then reveals the Little Dipper asterism. Another pair of stars, Megrez and Phecda, point the way to Regulus , the brightest star in the zodiacal constellation of Leo, and Alphard, the brightest star in the largest constellation of the sky, Hydra. The line from Megrez to Dubhe points the way to Capella in the constellation of Auriga, and one drawn from Megrez to Merak leads to Castor in the zodiacal constellation of Gemini.
The bright stars that form the Big Dipper asterism are relatively close to each other, from our perspective here on Earth. Some of these stars are among the brightest in the night sky. Alioth , designated as Epsilon Ursae Majoris, is the brightest star in Ursa Major, and the brightest of the seven stars of the Big Dipper asterism. Alioth is a blue-white giant or subgiant star with a peculiar spectrum, having calcium K-lines in it.
It is located at 86 light-years from Earth, and it is times brighter than our Sun. Alioth has an apparent magnitude of 1. Alioth, along with Dubhe, and Alkaid, are among the 58 navigational stars selected for celestial navigation. Only the brightest and the most easily recognizable stars are part of this group.
It is also a spectroscopic binary star system, being the 33 rd brightest star in the night sky, sharing this title with Mirfak, the brightest star in the constellation of Perseus. Dubhe, along with Merak, are known as the Pointer Stars which are used to find the north pole star which is currently Polaris.
The primary star, Dubhe A, is an orange giant star having an apparent magnitude of 1. Dubhe is located at around light-years away from us, and it is around times brighter than our Sun. Dubhe is situated in the bowl of the Big Dipper asterism.
It is a bluish-white subgiant star that has exhausted its hydrogen supplies, and thus it has begun to cool down. Merak is one of the four stars which form the bowl of the Big Dipper. Merak is located at around Phecda, designated as Gamma Ursae Majoris, is an Ae star, which is surrounded by an envelope of gas that is adding emission lines to its spectrum. Phecda is the sixth brightest star in Ursa Major, having an apparent magnitude of 2. The star is located at around It is 65 times brighter than our Sun.
It is the 11 th brightest star in Ursa Major. Megrez is a hydrogen-fusing dwarf still on the main sequence, located at around Megrez is a young star, having an estimated age of million years. Megrez is the 11 th brightest star in Ursa Major, the upper left star of the Big Dipper bowl, connecting the bowl to the handle, formed by the brighter Alioth, Mizar, and Alkaid. While even the oldest possible star chart we know of is over 32, years old, it still shows a constellation that looks remarkably like Orion.
But the basic fact is that the stars, much like our own planet and sun and everything else in universe, are constantly moving, even if that movement can take tens of thousands of years to become apparent. The above GIF shows how the Big Dipper, perhaps the most recognizable constellation in the sky, has changed over the past , years and will change over the next , The time spans involved resists most of our basic conceptions of civilization or human memory.
Even if you take a neolithic 30, BCE mammoth tusk as being our earliest star chart, the Big Dipper still looks a lot like the Big Dipper. But if humans manage to stick around the Big Dipper will become first become something more like a small ladle—its main stars shallowing out over thousand of years—and if we make it to 98, CE, the Big Dipper starts to look more like a large kitchen knife.
This is partly because the stars that make up the Big Dipper are relatively close to Earth—most are only light years away, so their movement is more apparent.
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