How Close Are We To Nuclear Fusion?

A galaxy cluster or cluster of galaxies is a structure that consists of anywhere from hundreds to thousands of galaxies bound together by gravity.[1] They are the largest known gravitationally bound structures in the universe and were the largest known structures in the universe until the 1980s when superclusters were discovered.[2] One of the key features of clusters is the intracluster medium or ICM. The ICM consists of heated gas between the galaxies and has a temperature on the order of 7-9 keV. Galaxy clusters should not be confused with star clusters such as open clusters, which are structures of stars within galaxies, as well as globular clusters, which typically orbit galaxies. Small aggregates of galaxies are referred to as groups of galaxies rather than clusters of galaxies. The groups and clusters can themselves cluster together to formsuperclusters.

The Andromeda Galaxy (/ænˈdrɒmɨdə/), also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth.[4] It is the nearest major galaxy to the Milky Way and was often referred to as the Great Andromeda Nebula in older texts. It received its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. Being approximately 220,000 light years across, it is the largest galaxy of the Local Group, which also contains the Milky Way, the Triangulum Galaxy, and about 44 other smaller galaxies.

The Andromeda Galaxy is the most massive galaxy in the Local Group as well.[7] Despite earlier findings that suggested that the Milky Way contains more dark matter and could be the most massive in the grouping,[12] the 2006 observations by the Spitzer Space Telescope revealed that Andromeda contains one trillion (1012) stars:[9] at least twice the number of stars in the Milky Way, which is estimated to be 200–400 billion.[13]

The Andromeda Galaxy is estimated to be 1.5×1012 solar masses,[7] while the mass of the Milky Way is estimated to be 8.5×1011 solar masses. In comparison, a 2009 study estimated that the Milky Way and M31 are about equal in mass,[14] while a 2006 study put the mass of the Milky Way at ~80% of the mass of the Andromeda Galaxy. The Milky Way and Andromeda are expected to collide in 3.75 billion years, eventually merging to form a giant elliptical galaxy [15] or perhaps a large disk galaxy.[16]

At 3.4, the apparent magnitude of the Andromeda Galaxy is one of the brightest of any Messier objects,[17] making it visible to the naked eye on moonless nights even when viewed from areas with moderate light pollution. Although it appears more than six times as wide as the full Moon when photographed through a larger telescope, only the brighter central region is visible to the naked eye or when viewed using binoculars or a small telescope.

Throwback Thursday: Do you really love science?

“That’s okay, because you’re a scientist! Your old theory — or way of making sense of the world — now gets revised, and replaced with a new one that’s even better at describing the full suite of phenomena you’re aware of.”

When you first venture out into the world, you’re armed, as a human being, with an incredible intelligence, but with no experience. All sorts of basic things must be learned, often the hard way: hot things will burn you, hot things that don’t look hot will also burn you, and that even very cold things will burn you, too. Figuring those things out – and the process by which you learn them – is science, in and of itself. But to move forward requires that we understand why, and that’s where scientific theories, leaps and even revolutions come into play. Don’t let bad science reporting take you away from what science is really all about: the knowledge and joy of figuring out how the world and Universe really works.

10 things you should know about black holes

“At this point in time, we are certain that black holes exist, we know where they are, how they form, and how they’ll eventually, on timescales of 10^67 years and up, cease to exist. But the details of where the information that went into them goes are still up for grabs, and that’s one of the problems unique to black holes among all objects in the Universe.”

Earlier this week, Stephen Hawking shook up the world when he announced that he had uncovered the solution to the black hole information paradox at a conference in Stockholm. When particles fall into (or create) a black hole, information is encoded on the black hole’s surface, but when the black hole decays into radiation, that information appears to be lost, as the radiation is thermal. But perhaps the information is stored on the event horizon, and can be encoded into the outgoing radiation thanks to the interplay of gravitation and matter. Details should be forthcoming in a paper to be released next month by Hawking, Malcom Perry and Andrew Strominger.

Record-Breaking Space Discoveries of 2016!

2016 was a lot of things, but for astronomers, it meant the discovery of some of the farthest, faintest, and youngest objects in the universe we’ve seen yet.

A new study of fossilized dinosaur embryos suggests that the young of these prehistoric animals were slow to develop, with some spending up to sixth months inside their eggs before hatching. Detailed in the journal Proceedings of the National Academy of Sciences, this drawn-out development cycle not only surprised scientists—it may have contributed to the downfall of the dinosaurs.

“We know very little about dinosaur embryology, yet it relates to so many aspects of development, life history, and evolution,” said study co-author Mark Norell, Macaulay Curator of Paleontology at the American Museum of Natural History. “This work is a great example of how new technology and new ideas can be brought to old problems.”

Using a combination of computed tomography (CT) scanning and powerful microscopes, Norell and colleagues from the University of Calgary and Florida State University examined the teeth of fossilized dinosaur embryos in unprecedented detail, shining new light on specimens about which not much is known.

Read more about this new research on the blog. 

A very interesting documentary about the Universe.

A nebula (Latin for "cloud";[2] pl. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Originally, nebula was a name for any diffuse astronomical object, including galaxies beyond the Milky Way. The Andromeda Galaxy, for instance, was referred to as the Andromeda Nebula (and spiral galaxies in general as "spiral nebulae") before the true nature of galaxies was confirmed in the early 20th century by Vesto Slipher, Edwin Hubble and others.

Most nebulae are of vast size, even hundreds of light years in diameter.[3] Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created in an Earthen environment - a nebular cloud the size of the Earth would have a total mass of only a few kilograms. Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions the formations of gas, dust, and other materials "clump" together to form larger masses, which attract further matter, and eventually will become massive enough to form stars. The remaining materials are then believed to form planets and other planetary system objects.

Dark matter is a hypothetical kind of matter that cannot be seen with telescopes but would account for most of the matter in the universe. The existence and properties of dark matter are inferred from its gravitational effects on visible matter, on radiation, and on the large-scale structure of the universe. Dark matter has not been detected directly, making it one of the greatest mysteries in modern astrophysics.

Dark matter neither emits nor absorbs light or any other electromagnetic radiation at any significant level. According to the Planck mission team, and based on the standard model of cosmology, the total mass–energy of the known universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.[2][3] Thus, dark matter is estimated to constitute 84.5% [note 1] of the total matter in the universe, while dark energy plus dark matter constitute 95.1% of the total mass–energy content of the universe.[4][5][6]

Forget the past, live the present, dream the future.

Maritina Christofilakou