Facts about Galaxy
The Milky Way galaxy is a member of an association named the Local Group, a relatively small group of galaxies that has a diameter of approximately one megaparsec.
The name is from the Greek root galaxias , meaning "milky," a reference to the Milky Way galaxy.
An Irr-I galaxy has some structure but does not align cleanly with the Hubble classification scheme.
At the other extreme, an Sc galaxy has open, well-defined arms and a small core region.
The Persian astronomer, Ab? Rayh?n al-B?r?n? (973-1048), proposed the Milky Way galaxy to be a collection of countless nebulous stars.
A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence.
An ultraviolet flare was observed when a star in a distant galaxy was torn apart from the tidal forces of a black hole.
Particularly, galaxy surveys in the zone of avoidance (the region of the sky blocked by the Milky Way) have revealed a number of new galaxies.
A lenticular galaxy is an intermediate form that has properties of both elliptical and spiral galaxies.
Ibn Qayyim Al-Jawziyya (1292-1350) proposed the Milky Way galaxy to be "a myriad of tiny stars packed together in the sphere of the fixed stars" and that these stars are larger than planets.
To remain gravitationally bound to such a group, each member galaxy must have a sufficiently low velocity to prevent it from escaping (see Virial theorem).
Instead, they gradually merge together to form a single, larger galaxy.
Solitary galaxies that have not significantly interacted with another galaxy of comparable mass during the past billion years are relatively scarce.
The word galaxy derives from the Greek term for our own galaxy, galaxias (????????), or kyklos galaktikos, meaning "milky circle" for its appearance in the sky.
Clusters of galaxies are often dominated by a single giant elliptical galaxy, known as the brightest cluster galaxy, which, over time, tidally destroys its satellite galaxies and adds their mass to its own.
The Milky Way galaxy is currently in the process of cannibalizing the Sagittarius Dwarf Elliptical Galaxy and the Canis Major Dwarf Galaxy.
The Milky Way and the Andromeda Galaxy are the two brightest galaxies within the group; many of the other member galaxies are dwarf companions of these two galaxies.
Among other things, it established that the missing dark matter in our galaxy cannot solely consist of inherently faint and small stars.
Hence starburst activity usually lasts for only about ten million years, a relatively brief period in the history of a galaxy.
An Sa galaxy has tightly wound, poorly-defined arms and possesses a relatively large core region.
An example of this is the ring galaxy, which possesses a ring-like structure of stars and interstellar medium surrounding a bare core.
Starburst galaxies are the result of such a galactic collision that can result in the formation of an elliptical galaxy.
Using a refined approach, Kapteyn in 1920 arrived at the picture of a small (diameter about 15 kiloparsecs) ellipsoid galaxy with the Sun close to the center.
A ring galaxy is thought to occur when a smaller galaxy passes through the core of a spiral galaxy.
Our own galaxy is a large disk-shaped barred-spiral galaxy about 30 kiloparsecs in diameter and a kiloparsec in thickness.
In bottom-up theories (such as the Searle-Zinn model), small structures such as globular clusters form first, and then a number of such bodies accrete to form a larger galaxy.
That is, a significant portion of the total energy output from the galaxy is emitted by a source other than the stars, dust and interstellar medium.
Such an event may have affected the Andromeda Galaxy, as it displays a multi-ring-like structure when viewed in infrared radiation.
A galaxy is a massive, gravitationally bound system consisting of stars, an interstellar medium of gas, plasma, and dust, and dark matter.
Bars are thought to be temporary structures that can occur as a result of a density wave radiating outward from the core, or else due to a tidal interaction with another galaxy.
Blazars are believed to be an active galaxy with a relativistic jet that is pointed in the direction of the Earth.
Interactions between nearby galaxies, which may cause them to merge, may enhance star formation, producing a starburst galaxy.
A galaxy will continue to absorb infalling material from high velocity clouds and dwarf galaxies throughout its life.
The realization that we live in a galaxy, and that there were, in fact, many other galaxies, parallel discoveries that were made about the Milky Way and other nebulae in the night sky.
The Milky Way galaxy appears to harbor at least one such object within its nucleus.
Instead the galaxy is dominated by generally older, more evolved stars that are orbiting the common center of gravity in random directions.
Curtis noticed that these novae were, on average, 10 magnitudes fainter than those that occurred within our galaxy.
Many dyed their hair red with henna and sprinkled it with gold powder, often adorning it with fresh flowers.
A radio galaxy emits radio frequencies from relativistic jets.
Within a billion years of a galaxy's formation, key structures begin to appear.
The detailed process by which such early galaxy formation occurred is a major open question in astronomy.
Solitary galaxies that have not significantly interacted with another galaxy of comparable mass during the past billion years are relatively scarce.
Our Solar System consists of our star, the Sun, and its orbiting planets (including Earth), along with numerous moons, asteroids, comet material, rocks, and dust. Our Sun is just one star among the hundreds of billions of stars in our Milky Way Galaxy.
To understand you need to know exactly where we live in neighborhood of the Milky Way Galaxy. As we are part of the solar system Earth pretty much follows the path of the sun as it goes through its own orbit around the galaxy. The Milky Way is a spiral galaxy type so it has arms sort of like an octopus.Sep 26, 2010
What Is the Biggest Thing in the Universe? Scientists have created the first map of a colossal supercluster of galaxies known as Laniakea, the home of Earth's Milky Way galaxy and many other. ... In the cosmic scheme of things, Earth is small.Jan 17, 2018
Milky Way Galaxy Has Four Spiral Arms, New Study Confirms. A 12-year study published in the Monthly Notices of the Royal Astronomical Society has confirmed that our Milky Way Galaxy has four spiral arms, following years of debate that it has only two arms.Dec 29, 2013
The Orion Arm is a minor spiral arm of the Milky Way some 3,500 light-years (1,100 parsecs) across and approximately 10,000 light-years (3,100 parsecs) in length. The Solar System, including the Earth, lies within the Orion Arm.
M31.html. The Andromeda Galaxy is the most distant object you can see with your naked eyes, two million light years away. It is visible as a dim, fuzzy star from a dark sky site. With binoculars you can clearly see the elliptical shape of the galaxy.
A galaxy contains stars, gas and dust. In a spiral galaxy like the Milky Way, the stars, gas, and dust are organized into a "bulge," a "disk" containing "spiral arms," and a "halo." Elliptical galaxies have a bulge-like central region and a halo, but do not have a disk. ... Some old stars are also present.
All in all, Hubble reveals an estimated 100 billion galaxies in the universe or so, but this number is likely to increase to about 200 billion as telescope technology in space improves, Livio said.Apr 1, 2014
Galaxy Formation. ... One says that galaxies were born when vast clouds of gas and dust collapsed under their own gravitational pull, allowing stars to form. The other, which has gained strength in recent years, says the young universe contained many small "lumps" of matter, which clumped together to form galaxies.
This classification system is known as the Hubble Sequence. It divides galaxies into three main classes with a few variations. Today, galaxies are divided into four main groups: spiral, barred spiral, elliptical, and irregular.
Astronomers have crowned the universe's largest known spiral galaxy, a spectacular behemoth five times bigger than our own Milky Way. The title-holder is now NGC 6872, a barred spiral found 212 million light-years away in the southern constellation Pavo, researchers announced today (Jan. 10).Jan 10, 2013
100 thousand million stars
The name of our galaxy is the Milky Way. Our Sun and all of the stars that you see at night belong to the Milky Way. When you go outside on a dark night and look up, you will see a milky, misty-looking band stretching across the sky.
The Romans named it via lactea precisely because it looks like a milky patch of sky above the Earth at night. But, the Romans weren't the first to name the galaxy. The Romans got the name from the Greeks, who called it galaxias kyklos, which translates into “milky circle.”Nov 13, 2013
From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610. Until the early 1920s, most astronomers thought that the Milky Way contained all the stars in the Universe.