Cartwheel Galaxy, Result Of A Violent Galactic Collision.

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Cartwheel Galaxy
Located about 500 million light years away in the constellation Sculptor, the cartwheel shape of this galaxy is the result of a galactic collision between two galaxies that happened almost 200 million years ago. 

As pictured in this image taken by the Hubble Space Telescope, it's wheel like shape was formed when a smaller galaxy passed right through a large one and produced shock waves that move out the interstellar gas and dust to the edges, much like ripples formed when a stone is dropped into a lake. 

This huge amount compressed gas and dust sparked regions of intense star formations which is appearing blue in the image. The outermost ring of this galaxy is 1.5 times the size of our Milkyway, marks the shock wave’s leading edge.

The bright object in the center is the galaxy's nucleus and the spoke-like structures are materials connecting the nucleus to the outer ring of young stars. This celestial object is one of the most fantastic examples of the ring galaxies.

image credit: esa/hubble & nasa
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Study Shows, Milky Way Has Eaten 11 Other Galaxies.

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 Milky Way galaxy.
image source: pixabay.
You may have heard about the possible future merger of the Milky Way and the Andromeda galaxy, but the recent preliminary data released by the Dark Energy Survey shows that our home galaxy has already collided with another eleven galaxies.

During the survey, researchers found 11 new stellar streams, the remnants from smaller galaxies that the Milky Way has collided with and devoured. 

Launched in 2013 the Dark Energy Survey [DES] is an international collaboration of more than 400 scientists around the globe that aims to reveal the nature of the mysterious force of dark energy. 

The publicly released data consist hundreds of terabytes of images gathered during the first three years of the survey by using an extremely sensitive 570 Megapixel digital camera, known as the Dark Energy Camera or DECam. 

"There are all kinds of discoveries waiting to be found in the data," said Brian Yanny of Fermi National Accelerator Laboratory, DES data management project scientist. "While DES scientists are focused on using it to learn about dark energy, we wanted to enable astronomers to explore these images in new ways, to improve our understanding of the universe," he added.

Stellar Streams & Milky Way.

The magnificent Milky Way that we see today wasn't the same from day one, our home galaxy grows up to its current form by consuming other smaller galaxies and probably still doing so. As the gravitational pull of Milky Way torn apart the smaller galaxies, stars with in them form streams across the sky.

"We’re interested in these streams because they teach us about the formation and structure of the Milky Way and its dark matter halo. Stellar streams give us a snapshot of a larger galaxy being built out of smaller ones," said Nora Shipp, one of researcher from University of Chicago. 

Before this new discovery, only about two dozen stellar streams had been spotted in the past. 

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Light Pillars, An Optical Phenomenon Beyond Imagination.

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Light Pillars over Canada
Light Pillars over London Ontario, Canada. Photo by Ray Majoran/ CC BY

Sometimes nature creates more spectacular scenes than anything we can dream up in science fiction and Light pillars are definitely one of them.

Usually visible during very cold weather, light pillars are an atmospheric optical phenomenon where columns of light can be seen beaming directly upwards from a light source.

Light Pillars in Canada.
  Light Pillars in North Bay Ontario, Canada. Photo by Timmyjoeelzinga/ CC BY
This majestic phenomenon occurs when lights, both from natural and artificial sources interact with the numerous flat ice crystals in the atmosphere. These flat crystals are hexagonal in shape and float horizontally in the air close to Earth’s surface.

Photo by V1adis1av/ CC BY
Together the surface of million of tiny crystals act as a mirror and reflect light downwards to our eyes or camera. As the ice crystals float in the air at different heights, it creates a light column from the source.

Light Pillars in Stockholm, Sweden.
 Light Pillars during a cold January winter night in Stockholm, Sweden. Photo by Raitisfreimanis/ CC BY
Let's interpret this with a simple example, have you ever used a torch or flashlight in a dusty place? if yes, then you surely have seen the light beam emanating from the torch.

In a clean room we don't see this phenomenon but in not so clean room we do. It occurs only in dusty places because the dust floating in the air reflect the light and create a column.

Light pillars over USA
Light pillars over Laramie, Wyoming, USA in a winter night. Photo by Christoph Geisler/ CC BY
That's the same thing happens in Light pillars, just, in this case, ice plays the role of dust. One more plus point of ice is it reflects the exact same colour of the light source, which makes light pillars more alive.

10 Amazing Facts about the Ultimate High-Altitude Hike, Spacewalks.

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Astronaut on Spacewalk.
Image Credit: NASA
Spacewalks, which technically known as Extra-vehicular Activity [EVA] are the finest examples of human innovation and courage. During a spacewalk, astronauts witness a breathtaking view of Earth below them as they soar over the mountains, deserts, city lights, rivers and oceans experiencing a sunrise and a sunset in every 90 minutes. 

Spacewalks are mainly performed to carry out space station maintenance and science experiments outside the station, but sometimes it has also done to repair spacecraft and telescopes that are in space. So, here are the ten amazing facts about the ultimate high-altitude hike, spacewalks:-

1.Long training on Earth- 
Before launching to space, astronauts train for months and practice their spacewalks several times in an underwater simulated environment. Another way astronauts practice spacewalks is by using virtual reality. It's simulation looks and feels just like a spacewalk.

Astronauts practising EVA underwater
SM4 EVA Astronauts John Grunsfeld and Andrew Feustel practice installing Hubble’s new panchromatic imaging instrument, the Wide Field Camera 3, during final underwater training at the Neutral Buoyancy Laboratory at the Johnson Space Center in Houston, Texas. Image Credit: NASA.
2.Spacesuits, you can't dare to wear- 
During spacewalks, astronauts wear a spacewalking suit called Extravehicular Mobility Unit or EMU which acts as a life support system and protects them from the hazardous environment of space. While in space it weighs nothing, but on Earth these suits weighs around 280 pounds [127 kg], without the astronaut in it.

3.Preparation before a spacewalk takes hours- 

It takes almost 45 minutes to wear an EMU and even after putting it on, to get adapted to the lower pressure of the suit, an astronaut has to spend few more hours breathing pure oxygen before going outside of the space station. Breathing only oxygen also helps to get rid of all the nitrogen in an astronaut's body, which could cause body pain during the spacewalk.

4.How long they walk in space?
Usually, spacewalks last between 6 to 7 hours but can be extended to 8 hours, if necessary. The work timeline is designed to fulfil as many tasks as possible, as the astronauts have limited life support systems in the spacesuit.

Astronauts during an EVA
Astronauts Steven L. Smith and John M. Grunsfeld are photographed during an EVA during the December 1999 Hubble servicing mission of STS-103. Image Credit: NASA.
5.Eating and Drinking- 
Before a spacewalk astronauts eat light, usually something like a protein bar, some fruits and water. Their spacesuits also have a drink bag inside, with a bite valve that allows ready access to water.

6.Why spacesuits only come in white?

The reason that spacesuits are white because white colour reflects heat in space as the same it does here on Earth. During spacewalks astronauts face a wide variety of temperatures. In direct sunlight, the temperature can go up to 275°F [135°C] and in Earth orbit, conditions can be as cold as -250°F [-121°C].

Astronauts floating in space
Astronauts F. Story Musgrave, left, and Donald H. Peterson float in the cargo bay of the Earth-orbiting space shuttle Challenger during their April 7, 1983 extravehicular activity on the STS-6 mission. Their "floating" is restricted via tethers to safety slide wires. Image Credit: NASA.

7.Safety during the walking-
Astronauts use safety tethers to stay close to their spacecraft. One end of the tether is hooked to the astronaut, while the other end is attached to the spacecraft. The safety tethers protect astronauts from floating away into space.

8.And the best part, they also have Jetpacks-

To move around freely in space without any safety tethers astronauts use a jetpack-like device called the Manned Maneuvering Unit [MMU]. It uses small jet thrusters to move and has a control on the armrest to direct.

Astronaut using Manned Maneuvering Unit
Astronaut Dale A. Gardner, getting his turn in the Manned Maneuvering Unit, prepares to dock with the spinning WESTAR VI satellite during the STS-51A mission. Image Credit: NASA.
9.The first and the longest spacewalks-
The first person to go on an EVA was cosmonaut Alexei Leonov from Russia. It took place on March 18, 1965, and was 10 to 12 minutes long. The longest EVA was 8 hours and 56 minutes, performed by Susan J. Helms and James S. Voss on March 11, 2001.

10.The first spacewalk for an in-flight repair-

The first EVA where an astronaut performed an in-flight repair of a space shuttle was by American astronaut Steve Robinson on Aug. 3, 2005, during STS-114. Robinson removed two protruding gap fillers from space shuttle Discovery's heat-shield while the shuttle was docked to the International Space Station.

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Space Shuttle Atlantis Over The Andes Mountains.

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Image Credit: NASA
Flying above the Andes Mountains near the border of Argentina and Chile, the space shuttle Atlantis is shown making its relative approach to the International Space Station. This image was taken from ISS, during the STS-132 shuttle mission on 16 May 2010. 

Atlantis was named after the RV Atlantis, an exploration sailing ship of the Woods Hole Oceanographic Institute. 

In it's lifetime, Atlantis had travelled almost 126 millon miles or 203 millon km, which is nearly 525 times the distance from the Earth to the Moon.

Top 12 Most Astonishing Images Taken by Cassini.

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A still image from Cassini's Grand Finale film. Credit: NASA/JPL-Caltech/Space Science Institute
Launched on October 15, 1997, Cassini entered Saturn's orbit after a long interplanetary voyage on July 1, 2004. For the last 13 years, NASA's Cassini spacecraft has returned thousands of stunning images and made many scientific discoveries about the giant planet, its rings, moons and atmosphere. As Cassini begins its #GrandeFinale, here are top 12 most astonishing images highlighting its epic journey. 

12. A Giant Red Rose. 

Image Credit: NASA/JPL-Caltech/Space Science Institute
The spinning vortex of Saturn's north polar storm resembles a deep red rose surrounded by green foliage. This false-colour image was made by using a combination of spectral filters sensitive to wavelengths of near-infrared light.

11. Bull's-eye Moons.
Image Credit: NASA/JPL-Caltech/Space Science Institute
Like a cosmic bull's-eye, Enceladus and Tethys line up almost perfectly for Cassini's cameras. The image was obtained at a distance of approximately 2.1 million kilometers from Enceladus and 2.6 million kilometers from Tethys.

10. The Yin and Yang moon.
Image Credit: NASA/JPL-Caltech/Space Science Institute
In 2007, the Cassini captured this high-resolution view of the bright trailing hemisphere of Iapetus. Iapetus has also called the yin and yang of the Saturn moons because its leading hemisphere is dark and its trailing hemisphere is bright.

09. The Triple crescent Moons.
Image Credit: NASA/JPL-Caltech/Space Science Institute
A single crescent moon is a familiar sight in Earth's sky, but with Saturn's many moons, we can see three or even more. The three moons shown here are Titan Mimas and Rhea.

08. Tethys tops Saturn.
Image Credit: NASA/JPL-Caltech/Space Science Institute
An illusion of perspective, Saturn’s moon Tethys seems to hang above the planet's north pole. The image was taken with the Cassini's wide-angle camera on Jan. 26, 2015.

07. An Ice World with an Ocean.
Image Credit: NASA/JPL-Caltech/Space Science Institute
Dramatic plumes, both large and small, spray water ice and vapour from many locations along the famed 'tiger stripes' near the south pole of Saturn's moon Enceladus. 

06. A Glorious view.
Image Credit: NASA/JPL-Caltech/Space Science Institute
Cassini delivered this glorious view of Saturn, on October 17, 2012, while the spacecraft was in Saturn's shadow. Since images like this can only be taken while the sun is behind the planet, there are only two times Cassini has captured a view like this.

05. Saturn approaching its northern Summer.
Image Credit: NASA/JPL-Caltech/Space Science Institute
This Natural view shows Saturn's northern hemisphere and its shadow on the rings as Saturn’s season advances toward northern summer. Saturn's year is nearly 30 Earth years long, and during its long time there, Cassini has observed winter and spring in the north, and summer and fall in the south. 

04. The Uranus from Saturn’s orbit.
Image Credit: NASA/JPL-Caltech/Space Science Institute
On April 11, 2014, Cassini captured this rare image of the blue ice-giant planet Uranus [indicated by a arrow] in the distance beyond Saturn’s rings. When this view was obtained, Uranus was nearly at a distance of 28.6 astronomical units from Saturn.

03. Catching the Tail.

Image Credit: NASA/JPL-Caltech/Space Science Institute
On February 25, 2011, Cassini captured this true-colour view where the huge storm was moving through the atmosphere in Saturn's northern hemisphere formed a tail that wrapped around the planet.

02. Earth as seen from Saturn.
Image Credit: NASA/JPL-Caltech/Space Science Institute
The tiny blue light indicated by the arrow is Earth as seen from Saturn, 1.44 billion kilometres [898 million miles] away. This iconic image was taken on July 19, 2013, by the wide-angle camera on Cassini spacecraft.

01. Saturn in a moment of Solar eclipse.
Image Credit: NASA/JPL-Caltech/Space Science Institute
As Saturn eclipsing the sun, Cassini captured this majestic moment on September 15, 2006, from its orbit. The night side of Saturn is seen to be partly lit by the light reflected from its own ring system. The rings themselves appear quite bright and slightly scattering the sunlight. Far in the distance, visible on the image left just above the bright main rings, [covered by a black box] is the almost ignorable presence of our home planet Earth. 

On this historic moment NASA also released a short animated video describing Cassini's Grand Finale.

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