2012


Like many of the most famous objects in the sky, globular cluster Messier 10 was of little interest to its discoverer. Charles Messier, the 18th century French astronomer, cataloged over 100 galaxies and clusters, but was primarily interested in comets. Through the telescopes available at the time, comets, nebulae, globular clusters and galaxies appeared just as faint, diffuse blobs and could easily be confused for one another.

Only by carefully observing their motion — or lack of it — were astronomers able to distinguish them: comets move slowly relative to the stars in the background, while other more distant astronomical objects do not move at all.

Messier’s decision to catalog all the objects that he could find, and that were not comets, was a pragmatic solution which would have a huge impact on astronomy. His catalog of just over 100 objects includes many of the most famous objects in the night sky. Messier 10, seen here in an image from the NASA/ESA Hubble Space Telescope, is one of them. Messier described it in the very first edition of his catalog, which was published in 1774 and included the first 45 objects he identified.

Messier 10 is a ball of stars that lies about 15,000 light-years from Earth, in the constellation of Ophiuchus (The Serpent Bearer). Approximately 80 light-years across, it should therefore appear about two thirds the size of the moon in the night sky. However, its outer regions are extremely diffuse, and even the comparatively bright core is too dim to see with the naked eye.

Hubble, which has no problems seeing faint objects, has observed the brightest part of the center of the cluster in this image, a region which is about 13 light-years across.

This image is made up of observations made in visible and infrared light using Hubble’s Advanced Camera for Surveys. The observations were carried out as part of a major Hubble survey of globular clusters in the Milky Way.

A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant flashenthunder. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon.

The F-1 engine -- the most powerful single-nozzle, liquid fueled rocket engine ever developed -- boosted the Saturn V rocket off the launch pad and onto the moon during NASA's Apollo program during the 1960s and 1970.

The F-1 Engine Powered Apollo Into History
Five F-1 engines were used in the 138-foot-tallS-IC, or first stage, of each Saturn V, which depended on the five-engine cluster for the 7.5 million pounds of thrust needed to lift it from the launch pad. The mighty engines, developed by engineers at NASA's Marshall Space Flight Center and its industry team, were fueled by a mixture of liquid oxygen and kerosene.

The cluster of five F-1 engines burned more than 15 metric tons of propellant per second during its two-and-one-half-minutes of operation. Each F-1 engine had more thrust than three space shuttle main engines combined to lift the vehicle to a height of about 36 miles and to a speed of about 6,000 mph.

The F-1 engine had roots outside NASA, born as an Air Force program developed by the aerospace firm Rocketdyne in 1955. NASA inherited it during a transfer of projects, conducted its own feasibility studies and awarded Rocketdyne a follow-on contract to step up work on the gargantuan propulsion system not long after NASA's formation, in 1960.

It’s famous that the universe is changeable: even the stars that become visible static and predictable every night are subject matter to change. This figure from the NASA Hubble Space Telescope shows planetary nebula Hen 3-1333. Planetary nebulae have not anything to do with planets — they truly represent the death throes of mid-sized stars like the sun. As they current out their outer layers, large, irregular globes of glowing gas develop around them, which appeared planet-like throughout the small telescopes that were used by their first explorers.
Nasa Space News -A Sheep in Wolf-Rayet's Clothing

The star at the heart of Hen 3-1333 is idea to have a mass of around 60% that of the sun, but not like the sun, its visible brightness varies significantly over time. Astronomers trust this variability is caused by a disc of dust which lies almost edge-on when vision from Earth, which occasionally obscures the star.

It is a Wolf–Rayet-type star — a late stage in the growth of sun-sized stars. These are named after (and share many observational personality with) Wolf–Rayet stars, which are a lot larger. Why the comparison? Both Wolf–Rayet and Wolf–Rayet type stars are hot and bright as their helium cores are showing: the former because of the strong stellar winds feature of these stars; the latter because the outer layers of the stars have been puffed left as the star runs low on fuel.

The showing helium core, rich with heavier elements, means that the exteriors of these stars are far hotter than the sun, typically 25,000 to 50,000 degrees Celsius (45,030 to 90,030 Fahrenheit). The sun has a moderately chilly surface temperature of just 5,500 degrees Celsius (9,932 Fahrenheit).

Many of the Universe's galaxies are like our own, displaying beautiful spiral arms wrapping around a bright nucleus. Examples in this stunning image, taken with the Wide Field Camera 3 on the NASA/ESA Hubble Space Telescope, include the tilted galaxy at the bottom of the frame, shining behind a Milky Way star, and the small spiral at the top center.


Other galaxies are even odder in shape. Markarian 779, the galaxy at the top of this image, has a distorted appearance because it is likely the product of a recent galactic merger between two spirals. This collision destroyed the spiral arms of the galaxies and scattered much of their gas and dust, transforming them into a single peculiar galaxy with a unique shape.

This galaxy is part of the Markarian catalogue, a database of over 1500 galaxies named after B. E. Markarian, the Armenian astronomer who studied them in the 1960s. He surveyed the sky for bright objects with unusually strong emission in the ultraviolet.

Ultraviolet radiation can come from a range of sources, so the Markarian catalog is quite diverse. An excess of ultraviolet emissions can be the result of the nucleus of an "active" galaxy, powered by a supermassive black hole at its center. It can also be due to events of intense star formation, called starbursts, possibly triggered by galactic collisions. Markarian galaxies are, therefore, often the subject of studies aimed at understanding active galaxies, starburst activity, and galaxy interactions and mergers.

NGC 6752 contains a high number of "blue straggler'' stars, some of which are visible in this image. These stars display characteristics of stars younger than their neighbors, despite models suggesting that most of the stars within globular clusters should have formed at approximately the same time. Their origin is therefore something of a mystery.

The above image looks like a hoard of gems fit for an emperor's collection, this deep sky object called NGC 6752 is in fact far more worthy of admiration. It is a globular cluster, and at over 10 billion years old is one the most ancient collections of stars known. It has been blazing for well over twice as long as our solar system has existed.

Studies of NGC 6752 may shed light on this situation. It appears that a very high number -- up to 38 percent -- of the stars within its core region are binary systems. Collisions between stars in this turbulent area could produce the blue stragglers that are so prevalent.

Lying 13,000 light-years distant, NGC 6752 is far beyond our reach, yet the clarity of Hubble's images brings it tantalizingly close.

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