The crowded heart of the Hercules globular cluster
This image, taken by the Advanced Camera for Surveys on the Hubble
Space Telescope, shows the core of the great globular cluster Messier 13
and provides an extraordinarily clear view of the hundreds of thousands
of stars in the cluster, one of the brightest and best known in the
sky. Just 25 000 light-years away and about 145 light-years in diameter,
Messier 13 has drawn the eye since its discovery by Edmund Halley, the
noted British astronomer, in 1714. The cluster lies in the constellation
of Hercules and is so bright that under the right conditions it is even
visible to the unaided eye. As Halley wrote: “This is but a little Patch, but it shews it self to the naked Eye, when the Sky is serene and the Moon absent.”
Messier 13 was the target of a symbolic Arecibo radio telescope message
that was sent in 1974, communicating humanity’s existence to possible
extraterrestrial intelligences. However, more recent studies suggest
that planets are very rare in the dense environments of globular
Messier 13 has also appeared in literature. In his 1959 novel, The Sirens of Titan, Kurt Vonnegut wrote “Every
passing hour brings the Solar System forty-three thousand miles closer
to Globular Cluster M13 in Hercules — and still there are some misfits
who insist that there is no such thing as progress.” The step from
Halley’s early telescopic view to this Hubble image indicates some
measure of the progress in astronomy in the last three hundred years.
picture was created from images taken with the Wide Field Channel of
the Advanced Camera for Surveys on the Hubble Space Telescope. Data
through a blue filter (F435W) are coloured blue, data through a red
filter (F625W) are coloured green and near-infrared data (through the
F814W filter) are coloured red. The exposure times are 1480 s, 380 s and
567 s respectively and the field of view is about 2.5 arcminutes
“ Seen from about 6 billion kilometers, Earth appears as a tiny dot (the blueish-white speck approximately halfway down the brown band to the right) within the darkness of deep space
Pale Blue Dot by Carl Sagan
From this distant vantage point, the Earth might not seem of any particular interest. But for us, it’s different. Consider again 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 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. 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. 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.
I HOPE YOU READ TO THE END PLEASE REBLOG SAVE THE EARTH
Long duration spaceflight takes a significant toll on the human body. It’s not like getting in a 20-meter sailboat and sailing around the world: you don’t feel the pull of gravity, bone density decreases, even the shape of the eye changes, affecting vision. In the entire history of human spaceflight, there have been only six people who have been on spaceflights of 300 or more days. If humans are to go to Mars or beyond one day, we need to know more about how long-duration spaceflight affects the human body.
That is why NASA and the Russian Federal Space Agency have teamed up for the Year in Space mission. NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko were launched into space on March 27, 2015 from the Baikonur Cosmodrome in Kazakhstan to spend a year living and working aboard the International Space Station. For comparison, a typical tour on the ISS lasts between 120 and 180 days. A manned mission to Mars is expected to last at least 500 days.
Several areas of study will be pursued over that year, including monitoring their performance of space station duties, the quality of exercise routines and sleep patterns, crew interactions, vision changes, metabolism, genetic makeup and psychology.
Astronaut Kelly’s identical twin brother Mark, himself a former astronaut, will serve as a control subject on Earth over the same time period, in order to closely monitor the differences between Earthbound and space-based subjects.
The data collected from the mission will have applications on Earth as well, including helping medical patients recover from long-term rest and potentially improving the health of patients with compromised immune systems.
September 27 will mark the halfway point in this historic mission. At the conclusion of the mission early next year, Scott Kelly will hold the record for spaceflight duration for an American, for both single spaceflights and cumulative time spent in space. He is a veteran of three spaceflights previously.
You can keep up with the Year in Space mission by following Scott Kelly on Instagram at stationcdrkelly or on Twitter @StationCDRKelly. -MAX
There is a new record holder for the title of smallest supermassive black hole, and it is RGG 118, located 340 million light years from Earth. It was discovered by a team using the Chandra X-Ray Observatory in Earth orbit and the 6.5-meter Clay Telescope in Chile.
RGG 118, the holder of this seemingly oxymoronic title, is estimated to have a mass approximately 50,000 times that of the Sun. The previous record holder for a black hole at the center of a galaxy is more than twice the mass of RGG 118.
Most galaxies, including the Milky Way, have supermassive black holes at their center. The black hole at the center of our home galaxy is even bigger - more than 100 times more massive than RGG 118. RGG 118 was discovered as part of 2013 study that searched for supermassive black holes in 25,000 dwarf galaxies.
The discovery will aid astronomers in their understanding of the formation of these supermassive black holes. The two leading theories are that they form when a massive cloud of gas and dust between 10,000 and 100,000 solar masses collapses in on itself, or they form when a giant star 100 solar masses or more runs out of fuel and collapses. Regardless of how they form, the data suggests black holes form symbiotic relationships with their home galaxies no matter what their size, regulating temperature and gravitational effects.
RGG 118 was discovered by using the Clay Telescope to look for cool regions near the center of galaxies, and the Chandra X-Ray Observatory to search for smaller structures - hot jets of gas - within those same regions. Black holes form when gravity overcomes the star’s outward internal pressure. Gravity near a black hole pulls anything near it inward, including gas and dust. This typically forms a vortex of inward falling matter. The dust and gas become heated and ionized, and that is what the Chandra orbiter was searching for.
RGG 118 is located in the constellation Serpens. -MAX
Gas giants bully smaller planets into giving them pebbles.
Planets come in all shapes and sizes – but how do gas giants become so big, whilst other planets remain comparatively small? New research has suggested that planets such as Saturn and Jupiter – the gas giants – form relatively quickly by gathering up small, pebble-sized bits of matter before their smaller siblings can get to them.
In a young planetary system, a star forms from a collapsing cloud of rotating gas. This spinning cloud of gas is surrounded by dust, which clumps together over time under its own gravity. These ‘clumps’ eventually form pebbles, asteroids and planets, which then orbit the newly-formed star. Exactly how the planets form is still a question that remains to be answered.
Gas giants are massive planets composed of mostly hydrogen and helium, with a rocky core. The first stage in forming these planets is the production of this core. Previously, scientists believed that the cores are formed via the accretion of dust from the solar nebula clumping together to form large, rocky chunks, which collapse under their own gravity. Over time, they slowly attract more and more mass to form planetary embryos called planetesimals. Once these planetesimals are large enough, they attract nearby hydrogen and helium to form gas giants. However, this model does not explain why gas giants are so big and other planets aren’t so much. New observational evidence suggests that gas giants actually form quite quickly after the formation of the host star, and up to 1000 times faster than previously thought.
The key to this swift formation, and the discrepancy in planetary sizes, is in the pebbles. Once large enough, the different sized planetesimals will form their own orbit around the burgeoning star; the largest of these go on to form gas giants. The pebbles, with their smaller size, don’t have the same defined orbit as they are smaller and therefore more unstable. They get easily disturbed by passing objects, as well as by the gas and dust that still surrounds the growing star. If a massive object passes by, the pebbles are easily attracted by its gravity. They get drawn in and add to its mass. The larger planetesimals attract pebbles much more strongly than the smaller ones, so the infant gas giants acquire more and more mass, whilst the smaller planets don’t get a look in. Essentially, the future gas giants barge through the pebbly path, scooping up pebbles and clearing the way before the smaller planets get the chance.
This new model paves the way to understanding the formation of our own solar system, as well as other planetary systems that might be out there.