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Most of the stars visible to the naked eye in the night sky are much larger, more luminous and brilliant than the Sun. However, despite often labelled as an average star the Sun actually outshines most stars in the galaxy. It's believed up to 80% of all stars in the Milky Way are red dwarfs. This type of star is so dim that not one is bright enough to be seen from Earth with the naked eye. Even Proxima Centauri, the closest star to the Earth after the Sun, requires optical aid to be seen. When it comes to solar twins or stars that are incredibly similar to the Sun across all parameters, not many exist. One of the best examples is 18 Scorpii.
Algol 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 magnitude +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.
The Perseid meteor shower is one of the finest annual meteor showers that's almost always reliable and produces a flux of fast and bright meteors. This year's maximum occurs on August 12th at 19 UT, although the 75% illuminated waning gibbous Moon in Pisces will interfere. The best time to look for meteors is during the early morning hours. The Perseids usually produce up to 80 meteors per hour at peak time. In addition, reasonable activity is also expected on the nights of August 11th/12th and August 13th/14th from all Northern Hemisphere locations. Recent analysis by NASA has rated the Perseids as the best meteor shower when it comes to fireballs.
For those at southern locations, the radiant remains low down or never even rises above the horizon. This considerably reduces the amount of visible meteors, although it's possible to spot a few of them coming up above the northern horizon.
Of all known multiple star systems consisting of at least three stars, probably the finest and most celebrated of all is Epsilon Lyrae (ε Lyr). This system, also known as the "Double Double" offers something for everyone from naked-eye observers to those with large telescopes.
When Sir William Herschel observed Mu Cephei in 1783 he described it as a most beautiful object of a very fine deep garnet colour, that's exceptionally striking when compared to nearby white stars. In fact, Mu Cephei is an extremely luminous red supergiant and one of the reddest known stars of all. It may be the largest star visible to the naked eye with an estimated radius of 1.15 billion kilometres (710 million miles) or 1,650 times that of the Sun.
Mercury remains visible in the early evening sky during the first part of August. From southern and tropical locations, the elusive planet can be seen low down towards the west-northwest horizon just after sunset. At the beginning of the month it shines at magnitude +0.4 and sets a couple of hours after sunset. By the second week, Mercury will be increasingly difficult to spot as it battles against the bright evening twilight. From mid-latitude northern temperate locations, the planet isn't well placed but can be spotted hugging the western horizon for a few days at the start of month.
Venus continues as a brilliant early morning object throughout August. The planet rises around 3 hours before sunrise from northern temperate locations, although considerably less from further south. Its magnitude dims slightly from -4.0 to -3.9 with the illuminated phase increasing from 74% to 83% as the month progresses.
On August 12th, Venus passes 2 degrees south of dwarf planet, Ceres. At magnitude +8.9, Ceres requires at least a pair of binoculars - but more likely a small telescope - to be seen. The waning crescent Moon passes 2 degrees south of the planet on August 19th. On the final day of the month, Venus is just over two degrees west of the large naked eye open cluster, M44, the Praesepe or Beehive.
How far away are the stars? This question, pondered by our ancestors for thousands of years, was only answered during the first half of the 19th century. In 1838, German mathematician and astronomer Friedrich Wilhelm Bessel made the breakthrough calculation. The star that went down in history was 61 Cygni.
61 Cygni was a prime candidate for distance measurement due to its large proper motion. Italian Catholic priest, mathematician and astronomer Giuseppe Piazzi first measured this, in 1804. He studied the star over a period of 10 years and realised it was moving faster than any known star at that time. Christened the "Flying Star", Piazzi's measurements initially gained little attention until Friedrich Wilhelm Bessel published an article in 1812.
Canopus is a brilliant star in the southern constellation of Carina and the second brightest in the night sky. At magnitude -0.72, it's about half as bright as Sirius but appearances can be deceptive; Canopus is far the more powerful star and Sirius only appears brighter because it's much closer to us. With a declination of -52 degrees, Canopus is best seen from southern latitudes. It can appear high in the sky from Australia, New Zealand, South Africa and much of South America. Indeed from such locations, the star is either circumpolar or only sets briefly.
Canopus can't be seen from most of Europe and many parts of the United States. For observers north of 38 degrees latitude, it never rises above the horizon. However, those living in southern Spain, southern Portugal, southern Florida, southern Texas and Hawaii can glimpse the star during the winter months. It's also visible from India, Pakistan and much of China and Japan.
From a historical perspective, Canopus can be seen from Alexandria but not from Athens. This provided early proof that the Earth is a globe and not a flat disk.
Alpha Centauri is the third brightest star in the night sky. To the naked eye it shines at apparent magnitude -0.27, which is fainter than Canopus (mag. -0.72) but brighter than Arcturus (mag. -0.04). However, Alpha Centauri is not a single star; it's a triple consisting of two bright components and a feeble red dwarf. For most of their orbit, the main stars are easily split with small telescopes. This is also the nearest star system to the Solar System.