A Patchwork of Galaxies - Halfway to the Edge of our Universe

In this image we see more than halfway to the edge of the observable Universe. This image is the result of 14 hour exposure of the Hubble Space telescope. Many of the objects are galaxies within this image are clusters about 5 billion light years away. The light from quasar QSO-160913+653228 took nine billion years to reach us and allows us to observe time on a truly cosmic scale. 

Credit: NASA,ESA,Hubble

What do you see in this image: a dolphin or a penguin?

This galactic pair has nicknamed after both of them – the curve of a porpoise or a dolphin can be seen in the blue- and reddish shape towards the bottom of the frame, when paired with the glowing orb just beneath it, resemble a bird or penguin guarding an egg.

The form of the penguin itself is made up of a single galaxy that has been distorted and ripped apart. This galaxy, named NGC 2936, was once a normal spiral like the Milky Way, until it started interacting with its egg-like neighbour, an elliptical galaxy named NGC 2937. Together, these two galaxies make up a pair dubbed Arp 142. 

The pair is pulling each other and interacting, slowly changing their appearances and disrupting their gas, dust and stars. In around a billion years these two might come together to form a single galaxy, and the merging process will be complete.

Credit: NASA/ESA/Hubble Heritage Team (STScI/AURA)

From Superbubbles to Galactic Fountains

Nebula NGC 1929 contains just the kind of superbubble that Astrophysicists think could cause a Galactic Fountain. Even though this nebula is not causing a fountain, it is theorized that similar nebula are causing Galactic Fountains within our Milky way galaxy. The illustration bellow shows how massive Galactic Fountains spew hot ionized gas away from our galactic disk to form Galactic Corona:

Supernova explosions within the galactic disc drive hot gas out of the disc, creating so-called galactic fountains that contribute to the formation of a halo of hot gas around the Milky Way. As the gas rises above and below the disc, reaching heights of a few kiloparsecs (more than 6,000 light-years!), it emits radiation and thus becomes cooler, condensing into clouds which then fall back into the disc, in a fashion that resembles a fountain.

Credit: ESO VLT/ESA/Fountains and Pumps

Celestial Spheres.

In the ancient world, the Circle was seen as the ideal form, so it influenced the view of the Solar System and the vision of heavens.
Ptolemy’s geocentric model, which was the prevailing view of the Solar System and Earth’s place in it for over 1400 years (until debunked by Copernicus), held that the Earth was static at the centre of the Universe, with all other bodies revolving around it in perfect circles. In the Ptolemaic system, the planets are assumed to move in a small circle called an epicycle, while epicycles rotated along a larger circle called a deferent, which in turn rotated around the Earth. The Earth then was like as the central hub of the Cosmos, everything else orbiting it eastward in uniform motion. This allowed Ptolemy to explain planetoids retrograde motion - the point at which planets seem to double back on their orbits at certain points in the year. 
With circles turning on circles at somepoint they seem to double back on themselves, which creates the idea of the spirograph like pattern in the design. 

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Look again at that dot. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every “superstar,” every “supreme leader,” every saint and sinner in the history of our species lived there- on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner, how frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Think of the rivers of blood spilled by all those generals and emperors so that, in glory and triumph, they could become the momentary masters of a fraction of a dot.

Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known so far to harbor life. There is nowhere else, at least in the near future, to which our species could migrate. Visit, yes. Settle, not yet. Like it or not, for the moment the Earth is where we make our stand.

It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known.

- Carl Sagan

In the latest episode of the web series Shelf Life, How To Time Travel To A Star, Museum astrophysicist Ashley Pagnotta introduces one of her areas of interest: Cepheid variable stars. In 1912 Henrietta Leavitt discovered a way for these stars to be used as distance markers in the cosmos while identifying and studying variable stars at the Harvard Observatory.

Cepheid variables can be used to map objects in space because they pulsate between dim and bright phases over a regular span of time, usually between one and 70 days. The period between the star’s consecutive brightest points can be used to determine the star’s luminosity, or brightness compared to the Sun. The brighter the star is, the longer it takes to swing between its brightest and dimmest points. With this information in hand, astronomers can reliably calculate how far from the Earth the star is.

Learn more about cepheid variables and Henrietta Leavitt on the Museum blog. 

Image: The Cepheid variable star RS Puppis, in an image captured by the Hubble Space Telescope, is one of the brightest in the Milky Way Galaxy.
© NASA

It can be seen with the naked eye in Centaurus, is 1300 times the diameter of Sol and one of the ten largest stars found. 50% larger than the famous red supergiant Betelgeuse and about one million times brighter than the Sun. HD 119796 a yellow hypergiant that cant last.

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