Perseus ArmThe Perseus Arm is one of two major spiral arms of the Milky Way galaxy. The second major arm is called the Scutum–Centaurus Arm. The Perseus Arm begins from the distal end of the long Milky Way central bar. Previously thought to be 13,000 light-years away from Earth, research published in 2005 has suggested that it is less than half that distance, estimated at 6,400 light years, from the Solar System.
Carina–Sagittarius ArmThe Carina–Sagittarius Arm (also known as the Sagittarius Arm or Sagittarius–Carina Arm, labeled -I) is generally thought to be a minor spiral arm of the Milky Waygalaxy. Each spiral arm is a long, diffuse curving streamer of stars that radiates from the Galactic Center. These gigantic structures are often composed of billions of stars and thousands of gas clouds.
Orion (constellation)Orion is a prominent set of stars visible during winter in the northern celestial hemisphere. It is one of the 88 modern constellations; it was among listed by the 2nd-century AD astronomer Ptolemy. It is named after a hunter in Greek mythology. Orion is most prominent during winter evenings in the Northern Hemisphere, as are five other constellations that have stars in the Winter Hexagonasterism.
Milky WayGalaxy containing the Solar SystemArtist's impression of the structure of the Milky Way based on data from the European Space Agency's Gaia telescope, including the location of the spiral arms, bar, and bulgeThe Milky Way or Milky Way Galaxy, or simply the Galaxy, is the galaxy that includes the Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars in other arms of the galaxy, which are so far away that they cannot be individually distinguished by the naked eye.
Orion NebulaThe Orion Nebula (also known as Messier 42, M42, or NGC 1976) is a diffuse nebula in the Milky Way situated south of Orion's Belt in the constellation of Orion, and is known as the middle "star" in the "sword" of Orion. It is one of the brightest nebulae and is visible to the naked eye in the night sky with an apparent magnitude of 4.0. It is 1,267.0 ± 5.4 light-years (388.5 ± 1.7 pc) away and is the closest region of massive star formation to Earth.
Galactic CenterThe Galactic Center is the barycenter of the Milky Way and a corresponding point on the rotational axis of the galaxy. Its central massive object is a supermassive black hole of about 4 million solar masses, which is called Sagittarius A*, part of which is a very compact radio source arising from a bright spot in the region around the black hole, near the event horizon.
Solar SystemThe Solar System is the gravitationally bound system of the Sun and the masses that orbit it, most prominently its eight planets, of which Earth is one. The Solar System is an isolated single-star planetary system (not part of a larger star system) within the Milky Way Galaxy. The system formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, creating the Sun and a protoplanetary disc from which the orbiting bodies assembled.
Norma ArmThe Norma Arm is a minor spiral arm of the Milky Way extending from and around its central hub region. The inner portion of the Arm is called the Norma Arm in narrow meaning. The outer end of it is identified either with the Cygnus Arm (not to be confused with local and minor Orion-Cygnus Arm), that lies outside the Perseus Arm, or the Outer Arm, which is located further away from the center of the Galaxy than the Cygnus Arm.
ParsecThe parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to 3.26 light-years or 206,265 astronomical units (au), i.e., 30.9 trillionkilometres (19.2 trillion miles). The parsec unit is obtained by the use of parallax and trigonometry, and is defined as the distance at which 1 au subtends an angle of one arcsecond (1/3600 of a degree).
Light-yearA light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly 9460730472580.8 km, which is approximately 9.46 trillion kilometres or 5.88 trillion miles. As defined by the International Astronomical Union (IAU), a light-year is the distance that light travels in vacuum in one Julian year (365.25 days). Despite its inclusion of the word "year", the term is a unit of distance, not a unit of time.
Astrophysical maserAn astrophysical maser is a naturally occurring source of stimulatedspectral line emission, typically in the microwave portion of the electromagnetic spectrum. This emission may arise in molecular clouds, comets, planetaryatmospheres, stellar atmospheres, or various other conditions in interstellar space.*As an Amazon Associate I earn from qualifying purchases.