SEVEN WONDERS OF THE UNIVERSE





Article by : Shanawaz Shaikh F. Y. BSc Jai Hind College , Mumbai , India.

"Science is the one human activity that is truly progressive , the body of positive knowledge is transmitted from generations to generations ." -Edwin Hubble







Space Shuttle Discovery carrying Hubble into orbit on 24 April , 1990.

THE HELIX NEBULA (EYE OF GOD)









Helix nebula seen through the visible filters by the Hubble Space Telescope.





The Helix nebula , also called as the eye of God ( or the eye of Sauron ) is a planetary nebula located in the constellation Aquarius . The term planetary nebula has nothing to do with planets , as these nebulas seen from the telescopes by astronomers in the 18th century resembled the shape of a planet , and hence the name .It was discovered by a German astronomer named Karl Ludwig Harding . It is about 655 light years away from the Earth (A light year is the distance that light travels in a year , about 9 trillion kilometers) . It is formed by an intermediate to low mass star , which sheds it's outer layers near the end of it's life , as it runs out out of Hydrogen and Helium to fuse .









THE CRAB NEBULA









Hubble Space Telescope mosaic image assembled from 24 individual exposures taken in October 1999 , January 2000 and December 20000 .





The crab nebula is a supernova remnant in the Taurus ( the bull ) constellation. It is also the first member of the Messier Catalogue , a compilation of 110 objects in the sky that are not to be confused with comets. At the heart of the crab nebula lies a neutron star , as it's name suggests , it is made up of mostly neutrons .A massive star is supported by the Gravitational pull inwards ( due to it's mass ) and the pressure outwards caused by the heat generated due to nuclear fusion . When such a star runs out of hydrogen to fuse , it explodes in a spectacular explosion , called a supernova , spewing it's outer layers into space . The remnants of the core coalesce to form a dense object , the star has become so dense that the protons and electrons combine to produce neutrons in the core of these stars , and hence the name , neutron stars . The neutron star inside the crab nebula rotates , and we call these rotating neutron stars pulsar . In this case , it's called a crab pulsar . This neutron star in the crab nebula rotates 30.2 times in a second , imagine such dense objects spinning so fast , how beautiful would it be . If the neutron star further collapses , it forms a black hole , a hole in space where the Gravity is so strong that even light cannot escape .





FUN FACT : The last element of the Messier catalogue is Andromeda , our neighbouring Galaxy .









CARINA NEBULA (The mystic mountains)









The mystic mountains are a dust and gaseous pillar in the Carina nebula , captured by HST on it's 20th anniversary .





The Carina nebula , also called as the grand nebula is a large complex area of bright and dark nebulosity ( the dust is so dense that it obscures the light emitted in the visible range from stars and nebula behind it ) located in the constellation of Carina . It is about 8500 light years from Earth . It was discovered by the French astronomer Nicolas Louis de Lacaille in 1752 from Cape of Good Hope , he also named 14 out of 88 constellations known today . The Carina nebula contains Eta Carina , a highly luminous and hypergiant star , with a mass of about 100 to 150 times that of the Sun , and luminosity four million times! I mean , imagine a star 4000000 times more bright and shiny than our own Sun , truly amazing ! This picture here is called mystic mountains , a pillar of dust and gas in the Carina nebula . These pillars are about 3 light years in height , stars inside these pillars emit jets of gas , streaming from towering peaks .





THE EAGLE NEBULA ( PILLARS OF CREATION )













The pillars of creation in the eagle nebula captured by the Hubble Space Telescope in 2014.





The Pillars of creation are described as the elephant trunks of the interstellar gas in the Eagle nebula , specifically the Serpens constellation . These are located about 6000 to 7000 lightyears away from the Earth . As the name suggests , these gaseous clouds are in a process of creating new stars , this is where stars are born , as the gaseous clouds coalesce due to the influence of gravity . The astronomers responsible for the picture are Jeff Hester and Paul Scowen from Arizona State University .The pillars are composed of molecular Hydrogen and dust being eroded by photoevaporation ( high energy radiation ionizes gas and causes it to move away from the ionizing radiation ) from the UV light of the close by stars . The leftmost pillar , the tallest one is about 4 lightyears in length , the finger like structures at the top of the clouds , the very tiny region of this picture , are larger than our Solar System . The lumps in those regions are called Evaporating Gaseous Globules (EGG'S) , the place where stars are formed .









HST image of the Pillars of Creation in Infrared light , that allows us to see the various dim stars in the background emitting infrared light .





In a celebration of the 25th anniversary since it's launch , astronomers revisited the Pillars of Creation which was unveiled in 2015 during American Astronomical Society meeting . The dust clouds in the picture that captures visible light obscures the star light from so many stars in the Pillars of Creation . Seeing it in Infrared light brings a new perspective into this picture, to see so many stars being born . Hubble has made us realize that different wavelengths of stars tell completely different stories, and Hubble has been unfolding them in its full glory!





THE CAT'S EYE NEBULA









Composite image using optical images from HST and the Chandra X- Ray telescope ( Named after Indian astrophysicist Subrahmanyan Chandrashekhar )





The Cat's Eye nebula is a planetary nebula in the northern constellation of Draco , discovered by William Herschel on 15 February , 1786 . It was the first nebula whose spectrum was analyzed by the astronomer William Huggins , to show that these nebulas are dusty gas clouds , and not star like in nature . His observations revealed that the spectrum was non-continuous and made of a few bright emission lines , indicating that the dust consisted of ionized gas . Like most astronomical objects , it consists mainly of hydrogen and helium gas , with other heavier elements in small quantities . Hydrogen in these gases , at higher temperature fuses to form helium , and helium fuses to form Oxygen and Sulphur and Carbon and Argon . The gold ornaments that you wear , the oxygen in the atmosphere , the Carbon that you and me are made of , every single element in the periodic table was cooked in the core of these stares and spewed out during massive supernova explosions ,

so not only you are within the Universe , the Universe is within you , amazing , right ?





BUBBLE NEBULA





Wide field image of the Bubble nebula captured by the HST .





The bubble nebula , also called as Sharpless 162 is an emission nebula . Emission nebula are formed of ionized gases and they emit light of many different wavelengths . It is located in the constellation of Cassiopeia . The bubble is created by a massive , hot central star and it is located near a giant molecular cloud ( a region of dust and gas in space where formation of molecules like H2 is favorable ) , while the hot central star causes it to glow . It was discovered in 1787 by the British astronomer , William Herschel . With an 8 or 10 inch mirror telescope , the nebula is visible as a very faint , but large shell around the central star . It is about 11000 lightyears away from Earth .





HUBBLE ULTRA DEEP FIELD













The original NASA release , containing galaxies of various shapes , sizes and colors . The smallest , reddest galaxies are the most distant ones , there are about 10,000 of these , some of them existing shortly after the Big Bang .





The Hubble Ultra Deep Field is an image of a small region of space , in the constellation Fornax , containing approximately 10,000 galaxies . The picture was released by combining the data from HST from September 24 , 2003 to January 23 , 2004 . Looking back about 13 billion years ( 800 million years after the Big Bang ) , it has been used to study galaxies at the very beginning of the Universe . Telescopes are like time machines , but you can only travel into the past , not into the future ( in order to travel in the future, go in the vicinity of a Black Hole , although I have a feeling that might be dangerous. ) The speed of light is constant in a vacuum , so as the light leaves a star and travels towards us , suppose it travels a distance of one light year , by the time it reaches us , we will not see the star as it is right now , but as it was a year ago , because that is the light that reached us . To see the star as it is now , we will have to wait another year , for light emitted at that point to reach us , how cool is that ! The Earth is about 4.5 billion years old , so imagine if I travel 4.5 billion light years into space , turn around and bring out the best telescopes , I won't be able to see the Earth , because the Earth hasn't formed yet , all I would see is a cloud of dust and gas , from which , in the next 4.5 billion years , Earth will be created , The HUDF is the deepest image of the Universe ever taken and has been used to search for galaxies that existed 400 to 800 million years after the

Big Bang .





THANK YOU NASA , for providing us with such splendid images, and allowing the general public to access those.





"The most incomprehensible thing about the Universe is that it is comprehensible."

-Albert Einstein.













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This year, we celebrate the long lasting legacy of the, which has been functioning for thirty years since it was launched on 24 April 1990 and providing us with amazing scientific data and beautiful snapshots of the Cosmos. Here we take a look at the most spectacular and elegant pictures taken by the Hubble Space Telescope , and what lies in the future of space based telescopes .The intention of the HST was to probe the Universe deeper and go beyond the atmosphere of the Earth, which makes it difficult to observe the Stars and Galaxies for many reasons , such as clouds , blocking of the UV light by the Ozone layer or refraction ( bending of light) through the atmosphere and much more...Hubble orbits the Earth in a low Earth orbit ( altitude of approximately 540 kilometers from the Earth's surface ) and it takes around 97 minutes to make a single revolution around the Earth. It has a 2.4 meters in diameter (about 8 feet) mirror which is much smaller than the ground based telescopes, but going above the atmosphere and the Ozone layer gives it a huge advantage to form clearer images . It is fine tuned to observe in Visible , UV and near Infrared part of the electromagnetic spectrum. Hubble produces pictures in black and white, and later astronomers assign colors to these pictures. If the picture is taken in visible range , they can assign it's true colors to the picture , but if it's in Infrared or UV, then colors are given to a specific wavelength of light., and the size of the Space Shuttle in which the telescope was launched limited the size of the telescope .The HST is named after American astronomer, whose discovery is considered to be one of the greatest in all of cosmology(Cosmology is the study of the Universe). In the earlier days, it was a prevailing belief that the Milky Way Galaxy is all there is, but Hubble proved that ours is not the only Galaxy, he worked out the distances to about 9 different galaxies, and now we know that there are about a 100 thousand million galaxies, each having a hundred thousand million stars in it. But his greatest contribution was something else. Analyzing the spectra obtained from the light emitted by these galaxies , he found out that all of these were shifted to the red end of the spectrum, and not only that , he found out the farther these galaxies were , the faster they were moving, and thus, and the more profoundly shocking implication was, it is accelerating. This is now known as the Hubble' law .To know more about the Hubble Space Telescope and other amazing telescopes by NASA , check out this article! https://physicsdiscussionclub.blogspot.com/2020/03/the-space-telescopes .html