Stars

Stars are the most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies. The age, distribution, and composition of the stars in a galaxy trace the history, dynamics, and evolution of that galaxy. Moreover, stars are responsible for the manufacture and distribution of heavy elements such as carbon, nitrogen, and oxygen, and their characteristics are intimately tied to the characteristics of the planetary systems that may coalesce about them. Consequently, the study of the birth, life, and death of stars is central to the field of astronomy.

Star Formation

Stars are born within the clouds of dust and scattered throughout most galaxies. A familiar example of such as a dust cloud is the Orion Nebula. Turbulence deep within these clouds gives rise to knots with sufficient mass that the gas and dust can begin to collapse under its own gravitational attraction. As the cloud collapses, the material at the center begins to heat up. Known as a protostar, it is this hot core at the heart of the collapsing cloud that will one day become a star. Three-dimensional computer models of star formation predict that the spinning clouds of collapsing gas and dust may break up into two or three blobs; this would explain why the majority the stars in the Milky Way are paired or in groups of multiple stars.

Black hole

BLACK HOLES ARE points in space that are so dense they create deep gravity sinks. Beyond a certain region, not even light can escape the powerful tug of a black hole's gravity. And anything that ventures too close—be it star, planet, or spacecraft—will be stretched and compressed like putty in a theoretical process aptly known as spaghettification.

There are four types of black hole: stellar, intermediate, supermassive, and miniature. The most commonly known way a black hole forms is by stellar death. As stars reach the ends of their lives, most will inflate, lose mass, and then cool to form white dwarfs. But the largest of these fiery bodies, those at least 10 to 20 times as massive as our own sun, are destined to become either super-dense neutron stars or so-called stellar-mass black holes.

Space station

Research & technology on the space station
The International Space Station is an unprecedented achievement in global human endeavors to conceive, plan, build, operate, and utilize a research platform in space. With assembly of station at completion, continuity of visiting vehicles, and support of a full-time crew of six, the era of utilization for research advances.

Become a space station research
Have an idea for an experiment, or to test an innovative technology on station? Wondering where to start? This page provides Information for prospective researchers to discover how NASA partners with industry, academia and federal, state, regional and local entities for ISS research and development.

Space travel

Space travel is nothing like in the movies. Getting from A to B requires complex calculations involving inertia and gravity—literally, rocket science—to "slingshot" from planet to planet (or moon) across the solar system. The Voyager mission of the 1970s took advantage of a rare alignment of Jupiter, Saturn, Uranus, and Neptune to shave off nearly 20 years of travel time. Space is also dangerous. More than 20 astronauts have died doing their job.

That hasn’t stopped people from signing up and blasting off. NASA’s shuttle program has ended, but private companies are readying their own space programs. A company called Planetary Resources plans to send robot astronauts to the Asteroid Belt to mine for precious metals. Another company named SpaceX is hoping to land civilian astronauts on Mars—the next human step into the solar system—in 20 years. NASA and other civilian companies are planning their own Mars missions. Maybe you’ll be a member of one? Don’t forget to bring your dog.

Our first steps into space began as a race between the United States and the former Soviet Union, rivals in a global struggle for power. Laika was followed into orbit four years later by the first human, Soviet Cosmonaut Yuri A. Gagarin. With Earth orbit achieved, we turned our sights on the moon. The United States landed two astronauts on its stark surface in 1969, and five more manned missions followed. The U.S.’s National Aeronautics and Space Administration (NASA) launched probes to study the solar system. Manned space stations began glittering in the sky. NASA developed reusable spacecraft—space shuttle orbiters—to ferry astronauts and satellites to orbit. Space-travel technology had advanced light-years in just three decades. Gagarin had to parachute from his spaceship after reentry from orbit. The space shuttle leaves orbit at 16,465 miles an hour (26,498 kilometers an hour) and glides to a stop on a runway without using an engine.

Bullet train

Maglev (derived from magnetic levitation) is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track, then another set to move the 'floating train' ahead at great speed taking advantage of the lack of friction. Along certain "medium range" routes (usually 200 to 400 miles (320 to 640 km)) Maglev can compete favorably with high-speed rail and airplanes.

Maglev systems have been much more expensive to construct than conventional train systems, although the simpler construction of maglev vehicles makes them cheaper to manufacture and maintain.^{[citation needed]}Despite over a century of research and development, maglev transport systems are in operation in just three countries (Japan, South Korea and China). The incremental benefits of maglev technology have often been hard to justify against cost and risk, especially where there is an existing or proposed conventional high speed train line with spare passenger carrying capacity, as in high-speed rail in Europe, the High Speed 2 in the UK and Shinkansen in Japan.

• Electromagnetic suspension (EMS), electronically controlled electromagnets in the train attract it to a magnetically conductive (usually steel) track.
• Electrodynamic suspension (EDS) uses superconducting electromagnets or strong permanent magnets that create a magnetic field, which induces currents in nearby metallic conductors when there is relative movement, which pushes and pulls the train towards the designed levitation position on the guide way.

Space holes

*A "Dense Bullet of Something" Blasted Holes in the Milky Way*

Dan Robitzski in Off World

*Bullet holes*

Scientists say that something mysterious punched gigantic, cosmic “bullet holes” in parts of the Milky Way.

There’s a string of holes in a long stream of stars called GD-1 that suggests that some yet-undiscovered thing blasted its way through, according to researchpresented to the American Physical Society last month. Harvard-Smithsonian astrophysicist Ana Bonaca, the scientist who discovered the cosmic crime scene, suspects that the gigantic “bullet holes” may have been carved out by invisible dark matter.

*Whodunnit*

Unfortunately, the culprit of this celestial shooting seems to have gotten away with it — Bonaca told Live Science that there’s no evidence at the crime scene beyond the size of the gaps in the stellar stream.

“We can’t map [the impactor] to any luminous object that we have observed,” Bonaca told Live Science. “It’s much more massive than a star… Something like a million times the mass of the Sun. So there are just no stars of that mass. We can rule that out. And if it were a black hole, it would be a supermassive black hole of the kind we find at the center of our own galaxy.”

*Dark hammer*

Because there’s no evidence of such a black hole, Bonaca suspects a ball of dark matter may have crashed through the stars. But it’s too early to definitively rule out any possibilities

Astronomy

Astronomy is the scientific study of celestial objects (such as stars, planets, comets, and galaxies) and phenomena that originate outside the Earth's atmosphere (such as the cosmic background radiation).

It is concerned with the evolution, physics, chemistry, meteorology, and motion of celestial objects, as well as the formation and development of the universe.

Astronomy is one of the oldest sciences.

Astronomers of early civilizations performed methodical observations of the night sky, and astronomical artifacts have been found from much earlier periods.

However, the invention of the telescope was required before astronomy was able to develop into a modern science.

Historically, astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, and even, at one time, astrology, but professional astronomy is nowadays often considered to be identical with astrophysics.

Since the 20th century, the field of professional astronomy split into observational and theoretical branches.

Observational astronomy is focused on acquiring and analyzing data, mainly using basic principles of physics.

Theoretical astronomy is oriented towards the development of computer or analytical models to describe astronomical objects and phenomena.

The two fields complement each other, with theoretical astronomy seeking to explain the observational results, and observations being used to confirm theoretical results.

Amateur astronomers have contributed to many important astronomical discoveries, and astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery and observation of transient phenomena.

The most frequently studied star is the Sun, a typical main-sequence dwarf star of stellar class G2 V, and about 4.6 Gyr in age.

A sufficiently dense, and hot, core region will trigger nuclear fusion, thus creating a main-sequence star.

Almost all elements heavier than hydrogen and helium were created inside the cores of stars.

Note:   The above text is excerpted from the Wikipedia article "Astronomy", which has been released under the GNU Free Documentation License.