Check out the guide to astrophotography here.
THE ORION (Messier 42)
The Orion Nebula (aka. M42) located right below Orion’s Belt, can be seen with the naked eye as a fuzzy patch surrounding the star Theta. It is nearly a degree across in the sky, which makes it even larger than the full moon (although the moon appears to be larger because it is brighter). It is one of the brightest HII regions, being composed mainly of ionized hydrogen which gives off the dominant red glow. The energy to keep the nebula glowing comes from the very hot young stars in a formation called The Trapezium. M42 probably contains several hundred stars younger than a million years. Stars are still bei ng born in a dense cloud behind the nebula, but they are hidden from our view by a concentration of dust which reduces their light only to a million-millionth of its original intensity. Fortunately, astronomers have, with the help of infrared cameras, seen beyond the dust cloud and revealed the stellar nursery in all its glory.
RHO-OPHIUCHI
Rho Ophiuchi (ρ ophiuchi) is a multiple star complex, found rising above the plane of the milky way in the sky, as a part of the constellation Ophiuchus – The Serpent Bearer. It is one of the most vibrant and colourful nebulas in space, and one of the nearest star-forming regions to earth, about 400 light years away; allowing us to resolve much more detail.The interstellar clouds of gas and cosmic dust that make up Rho Ophiuchi contain emission nebulae that are rich in red, glowing hydrogen gas and blue reflection nebulas that reflect starlight from their surroundings. After forming along a large cloud of molecular hydrogen gas, young stars heat the surrounding dust to produce the infrared glow. And due to the different wavelengths of infrared light, an amazing variety of colour is seen. It also consists of numerous light and dark brown dust lanes. The dark-brown regions in the cloud complex consist of interstellar dust grains that prevent any light from passing through.
Stars in the process of formation, called young stellar objects or YSOs, are embedded in the pinkish nebulae which are otherwise hidden from the eyes of optical telescopes. Many of them are still enveloped in their own compact nebulae. In visible light, these YSOs are completely hidden in the dark nebula that surrounds them. But an exploration of the region in penetrating infrared light has detected newly formed stars whose average age is estimated to be 300,000 years, which is extremely young compared to the sun’s age of 5 billion years.
THE DOUBLE CLUSTER
At a distance of about 7650 light years, within the Perseus Arm, lies the Double Cluster, consisting of two open clusters NGC 689(h Persei) and NGC 884(Chi Persei). An open cluster is a group of up to a few thousand loosely bound stars that were formed from the same giant molecular cloud and have roughly the same age. Based on their individual stars, the two clusters are relatively young, both about 12.8 million years old. The clusters are blue-shifted which means that they are moving towards earth. The clusters are dominated by bright blue stars and, speckled with a few fine orange stars, make a spectacular sight in the night sky, especially through binoculars. The Double Cluster is continuously above horizon from most northern temperate latitudes. It is easy to spot in the northern winter sky between the constellations of Perseus and Cassiopeia. It represents the jeweled handle of the sword of Perseus, the son of the Greek god Zeus. Interestingly, it is not included in the popular Messier’s catalog but is included in the Caldwell catalog and thus it also goes by the name Caldwell 14.
TRIFID NEBULA (Messier 20)
Discovered by Charles Messier in 1764, M20 is a star-forming nebula located 9,000 light-years away from Earth in the constellation Sagittarius. Also known as the Trifid Nebula, M20 has an apparent magnitude of 6.3 and can be spotted with a small telescope.The nebula’s name means “divided into three lobes,” and refers to the object consisting of three types of nebulae and an open star cluster. The open cluster is surrounded by an emission nebula, a reflection nebula, and a dark nebula within the emission nebula. The dark nebula consists of dust clouds that absorb and block light from the bright objects behind them. It is responsible for the apparent gaps in the larger emission nebula that give M20 its trifurcated look.The other two types of nebulae – emission and reflection – make M20 glow in different colours in images. Emission nebulae are energised by the ultraviolet light of nearby stars and usually appear red in photographs. These nebulae are clouds of extremely hot hydrogen gas and usually regions where new stars are being formed. The light of the stars illuminates the surrounding clouds, ionizing photons in large portions of the clouds. Reflection nebulae, which typically appear blue in images, consist mostly of clouds of interstellar dust. They are also usually star-forming regions, but unlike emission nebulae, reflection nebulae do not emit any light of their own, but simply reflect the light of nearby stars.
The Trifid Nebula is unique in that it is dominated by one massive central star, which is estimated to be only about 300,000 years old (in comparison, our Sun is a star that is about 5,000,000 years old). The formation of the embryonic stars in the Trifid Nebula is thought to have been triggered by this massive star.The Trifid Nebula has an estimated age of only 300,000 years, which makes it one of the youngest emission nebulae known.
WHIRLPOOL GALAXY (Messier 51A)
Messier 51a is popularly known amongst stargazers and astro-enthusiasts as the Whirlpool Galaxy! In a dark sky, it can be resolved through modern-day amateur telescopes. Located near the easternmost star of Ursa Major, Alkaid, the extensive spiral arms of this mystic galaxy have been the foremost point of study for researchers. These were believed to be formed due to its close interaction with M51b, which is a dwarf galaxy as seen in the picture. The winding arms are actually long lanes of stars and gas, laced with dust. It is also highlighted to have had an abundance of supernovae in recent years, namely 3, which occurred in 1994, 2005 and recently in 2011. Located barely 25-million light years away, with a stunning face-on view, M51a serves to be a superb candidate for astronomers and enthusiasts alike, to study star-formation as well as the classic spiral structure of galaxies.
NEEDLE GALAXY
First spotted in 1785 by Uranus’ discoverer, Sir William Herschel (1738-1822), NGC4565 is one of the most famous example of an edge-on spiral galaxy, oriented perpendicularly to our line of sight so that we see right into its luminous disc. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices(refers to a classical story concerning the hair of Berenice, the wife of Ptolemy III of Egypt). At a distance of only about 40 million light-years, NGC 4565 is relatively close by, making it more luminous than Messier 31, the Andromeda Galaxy. Spanning 100,00 light-years, it is none less than a whopper- about a third larger than the Milky Way. Most speculating part is the galaxy’s boxy, bulging central core that juts out above most impressive dust lanes. It has a population of roughly 240 globular clusters, more than the Milky Way. It is confirmed to have two satellite galaxies, one of which is interacting with it via gravitational waves.It’s number 38 in the Caldwell catalogue and is best seen from northern locations during the months of March, April and May. Easily spotted with small telescopes owing to its closeness,size, and a visual magnitude of 9.5 , sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed in his catalogue.
THE PLEIADES (Messier 45)
“The Pleiades star cluster”, also known as the seven sisters and Messier 45 is a conspicuous object in the night sky which is open star cluster nearest to earth and visible with the unaided eye in the night sky located in constellation of Taurus which is approximately 445 l.y. away from earth with magnitude 1.6 declined at 24 degrees and 7 minutes,has a core of approx 8 l.y. radius.Galileo Galilei was the first astronomer to observe M45 through telescope.Contains a number of hot luminous B-type stars . The 9 brightest stars in the messier taken from greek mythology represent the seven sisters-Asterope, Electra, Mereope, Maia, Caleno, Taygeta and Alcyone and their parents,Pleione and Atlas.
M45 has a faint reflection nebula surrounding it named Maia Nebula ,it’s not related to the clusters indicated by its different radial velocity than cluster itself which means just they are crossing each other.The brightest reflection nebula in M45 is the Merope Nebula,surrounding star Mereope, it’s also known as Tempels Nebula.
Up to 25 percent of the stars in pleiades are brown dwarfs,one of the stars in the cluster was seen to be surrounded by PLANETESIMALS.It is also home to large X-ray source which are usually associated with stars that explode as supernovae .They are powered by dust and gas accelerated objects like neutron stars or black holes.
M45 has the estimated age of 150 million years.These stars formed last 100 million years and they will stay gravitationally bound to each other for approx another 250 million years before the cluster disappears as a result of tidal interactions with other objects in the neighbourhood .By that point the cluster will move from Taurus to Orion.
HERCULES GLOBULAR CLUSTER (Messier 13)
First of all, it is M13,”Hercules Globular Cluster”. The M stands for Messier (no it is not because it is untidy in the sky). Messier, as in Charles Messier, was a person who was interested in finding only comets and whatever wasn’t one, he put them all in a catalogue, unsurprisingly called the Messier Catalogue. This currently contains 110 things (all as interesting as the next). So let me tell a bit about M13, also known as the Great Cluster in Hercules.
Starting off on a historical note, it was discovered by Edmond Halley in 1714, who noted that ‘it shows itself to the naked eye when the sky is serene and the Moon absent.’ It makes sense since it has an apparent magnitude of 5.8(barely visible to the naked eye). So, where do we find it? It lies on the Keystone asterism (a lopsided square within the constellation Hercules ) and between the two bright stars Vega(of the Lyra fame) and Arcturus(of the Bootes constellation).
It is a globular cluster of several hundred thousand stars in the constellation of Hercules. What a globular cluster means is that it is a spherical collection of stars that orbits a galactic core. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes, and relatively high stellar densities toward their centres. To make the point clearer, the stellar density in the M13 is more than a hundred times more than that in the neighbourhood of the sun. In fact, they are so densely packed that stars sometimes collide so as to give rise to new stars, cutely referred to as the “blue stragglers”. These are of immense interest to many astronomers.M13 is 22,200–25,000 light-years away from Earth, which means that the best way to see M13 is through telescopes with large apertures. And has an estimated age of 11.65 billion years, which makes them one of the oldest inhabitants of our Milky Way.
And the final cool fact, that out of all of those stars there stands one stranger – Barnard 29. This spectral type B2 star is a young, blue star that M13 is believed to have collected during one of its tours around the Milky Way Galaxy.
VENUS TRANSIT
Venus Transit takes place when the planet Venus passes directly between the Sun and a superior planet. During a transit, Venus can be seen from Earth as a small black dot moving across the face of the SuN.The duration of such transit is usually several hours. The last transit of Venus was on 5 and 6 June 2012, and it was the last transit of the 21st century; the next transit will take place on 10-11 December 2117. A transit is similar to a solar eclipse by the Moon. Venus appears smaller and travels more slowly across the face of the Sun, because it is much farther away from Earth. Transits occur in a pattern that generally repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 incommensurabilities.
THE SATURN
Arguably the most beautiful object in the Solar System, it is the sixth planet from the Sun and is named after the Roman deity of wealth and agriculture.
As one of the five planets visible with the naked eye, it was known to the ancients though its dazzling rings were not discovered until the Dutch physicist and astronomer Christian Huygens observed them in 1659. One of the favorites of amateur astronomers, its rings can easily be seen even through a small telescope and are a treat for the eyes. More than 60 known moons are also home to some of the most exotic and exciting worlds including the likes of Titan and Enceladus which are thought to be potential candidates for extraterrestrial life.
Saturn is 9.5 ‘Astronomical Units’ away from the Sun meaning it is 9.5 times as far from the sun as Earth is. Similar to Jupiter, it is also a “Gas Giant” i.e. apart from its dense, metallic core, it is almost entirely made up of hydrogen and helium though it also has clouds made up of water droplets and ammonia. Although Saturn is not the only planet endowed with rings, no other planet has rings as complex and prominent as Saturn’s. The rings are not continuous structures, they are made up of billions of chunks of ice and rocks coated with dust. As many as 4 artificial satellites or probes have been sent to Saturn, the latest one being the Cassini-Huygens spacecraft which sent back valuable information and close up photos of Saturn and its moons.Fun Fact : At 0.7 g/cm3, the average density of Saturn is less than that of Water!