“The Stars, Like Dust, Encircle Me In Living Mists Of Light; And All Of Space I Seem To See In One

These Are The Oldest Footprints On Earth

Found on a prehistoric sea floor, the oldest footprints ever found were left between 551 million and 541 million years ago during the Ediacaran period. That is hundreds of millions of years before the dinosaurs.

The trackways tell scientists it was left by a bilaterian animal — that is, a creature with bilateral symmetry that has a head at one end, a back end at the other, and a symmetrical right and left side. Its paired appendages, scientists did not call them legs, were used to raise the animal off the sea floor as it moved.

Fontainebleau forest in France

All these are post-organic material: a petrified bones and organs of giants.

Orion Nebula in Oxygen, Hydrogen, and Sulfur via NASA https://ift.tt/2GB0bRc

Cover design for an Italian reprint of Isaac Asimov’s “Foundation Trilogy” by Gabriel Björk Stiernström. 

My God, it’s full of stars

- Dave Bowman, 2001 a Space Odyssey

When you look up from a dark site on a clear moonless night, the sky appears full of stars, almost too many to count.

It turns out that, with the naked eye, one can see anywhere between 5000 to 10000 stars, depending on whom you ask and how they estimate this number and just half of that on a given night because the Earth gets in your way. Still a lot but really nothing when you consider there are billions - maybe hundreds of billions of stars in our Galaxy and trillions of galaxies in the Universe.

It’s a completely different matter when you use optical aid. A pair of 50 mm binoculars can pull in some hundreds of thousands of stars; a small - say 80 mm telescope - like mine-can “ see” millions.

And here is an example. This is the much loved deep southern object known familiarly as 47 Tucanae- Tuc 47 to friends- and it is what is known as a globular cluster.

It contains over a million stars - I am unable to determine what the latest estimate is- a couple of decades ago we used to say it contained half a million stars but that estimate has since been upped.

It’s the second largest of this type of cluster- there are around 150 of these distributed in a halo around our galaxy that we know of.

And quite spectacular in a telescope of any size. It cannot but bring to mind Dave Bowman’s famous exclamation in “2001 a Space Odyssey “

Imaged from my backyard last weekend; an image salvaged despite the usual trials and tribulations that beset the amateur astrophotographer including tangled cables and the camera slamming into the tripod leg and so on and so forth.

Given the long weather forecast it’s going to be slim pickings this summer so you take what you get

What would it be like to live on a planet within a globular cluster? In 1941 Issac Asimov wrote a great short story “ Nightfall “ imagining just that. Highly recommended if you have forgotten it

Sadly the Hubble Space Telescope looked for planets in Tuc 47… and found none. So we have no evidence that planets form within these globular clusters- thus far

https://flic.kr/p/2mGS9cC

Gamma-ray Bursts: Black Hole Birth Announcements

Gamma-ray bursts are the brightest, most violent explosions in the universe, but they can be surprisingly tricky to detect. Our eyes can’t see them because they are tuned to just a limited portion of the types of light that exist, but thanks to technology, we can even see the highest-energy form of light in the cosmos — gamma rays.

So how did we discover gamma-ray bursts? 

Accidentally!

We didn’t actually develop gamma-ray detectors to peer at the universe — we were keeping an eye on our neighbors! During the Cold War, the United States and the former Soviet Union both signed the Nuclear Test Ban Treaty of 1963 that stated neither nation would test nuclear weapons in space. Just one week later, the US launched the first Vela satellite to ensure the treaty wasn’t being violated. What they saw instead were gamma-ray events happening out in the cosmos!

Things Going Bump in the Cosmos

Each of these gamma-ray events, dubbed “gamma-ray bursts” or GRBs, lasted such a short time that information was very difficult to gather. For decades their origins, locations and causes remained a cosmic mystery, but in recent years we’ve been able to figure out a lot about GRBs. They come in two flavors: short-duration (less than two seconds) and long-duration (two seconds or more). Short and long bursts seem to be caused by different cosmic events, but the end result is thought to be the birth of a black hole.

Short GRBs are created by binary neutron star mergers. Neutron stars are the superdense leftover cores of really massive stars that have gone supernova. When two of them crash together (long after they’ve gone supernova) the collision releases a spectacular amount of energy before producing a black hole. Astronomers suspect something similar may occur in a merger between a neutron star and an already-existing black hole.

Long GRBs account for most of the bursts we see and can be created when an extremely massive star goes supernova and launches jets of material at nearly the speed of light (though not every supernova will produce a GRB). They can last just a few seconds or several minutes, though some extremely long GRBs have been known to last for hours!

A Gamma-Ray Burst a Day Sends Waves of Light Our Way!

Our Fermi Gamma-ray Space Telescope detects a GRB nearly every day, but there are actually many more happening — we just can’t see them! In a GRB, the gamma rays are shot out in a narrow beam. We have to be lined up just right in order to detect them, because not all bursts are beamed toward us — when we see one it’s because we’re looking right down the barrel of the gamma-ray gun. Scientists estimate that there are at least 50 times more GRBs happening each day than we detect!

So what’s left after a GRB — just a solitary black hole? Since GRBs usually last only a matter of seconds, it’s very difficult to study them in-depth. Fortunately, each one leaves an afterglow that can last for hours or even years in extreme cases. Afterglows are created when the GRB jets run into material surrounding the star. Because that material slows the jets down, we see lower-energy light, like X-rays and radio waves, that can take a while to fade. Afterglows are so important in helping us understand more about GRBs that our Neil Gehrels Swift Observatory was specifically designed to study them!

Last fall, we had the opportunity to learn even more from a gamma-ray burst than usual! From 130 million light-years away, Fermi witnessed a pair of neutron stars collide, creating a spectacular short GRB. What made this burst extra special was the fact that ground-based gravitational wave detectors LIGO and Virgo caught the same event, linking light and gravitational waves to the same source for the first time ever!

For over 10 years now, Fermi has been exploring the gamma-ray universe. Thanks to Fermi, scientists are learning more about the fundamental physics of the cosmos, from dark matter to the nature of space-time and beyond. Discover more about how we’ll be celebrating Fermi’s achievements all year!

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How quickly do we grow accustomed to wonders. I am reminded of the Isaac Asimov story "Nightfall," about the planet where the stars were visible only once in a thousand years. So awesome was the sight that it drove men mad. We who can see the stars every night glance up casually at the cosmos and then quickly down again, searching for a Dairy Queen. (x)

QUETZALCOATLUS

Quetzalcoatlus goes down in history as the largest flying organism of all time, with a wingspan of 12 metres, which is larger than some planes. Quetzalcoatlus was the undisputed king of the Late cretaceous skies, so it seems fitting that its name is derived from an Aztec god, Quetzalcoatl. Although its wingspan is impressive, Quetzalcoatlus also had a huge 2.5 metre long skull, that is the average height of an Asian elephant! To get such a huge animal in the air, a complex system of air sacs was needed inside the bones, this meant that Quetzalcoatlus probably weighed no more than 250kg. Quetzalcoatlus, along with many pterosaurs, was originally thought to spend most of its time gliding over the oceans, skimming fish out from the surface of the water with their elongated beaks. However, due to the skull and beak morphology and the presence of fossils far inland it has become more widely accepted that Quetzalcoatlus stalked prey far below on the land. The fore and hind limb morphology of Quetzalcoatlus also suggests that they were competent walkers on the land, they would have stood up to 3 metres tall. 

The feeding habits of Quetzalcoatlus still remain something of a mystery. It was originally thought to be more of a scavenger, but the blunt beak was unsuited to stripping and picking flesh of a bony creature. It is more likely that Quetzalcoatlus hunted like modern-day storks, stalking the land from the skies above for smaller animals and then swooping down to eat them whole.

Jupiter Descending 

Cassini Observes Sunsets on Titan (Artist’s Rendering) by NASA on The Commons