Astronomy Reference Libraries

Page 16 of about 169 Articles
2004-10-19 04:45:40

Vega -- Vega (Alpha Lyrae) is the lead star in the constellation Lyra, reaching near directly overhead the mid-northern latitudes, during the summer. It's a "nearby star" at only 25 light years distant and together with Arcturus and Sirius, one of the brightest stars in the Sun's neighbourhood. Vega is a vertex of the Summer Triangle. Its spectral class is A0V (Sirius, an A1V, is slightly...

Trifid Nebula
2004-10-19 04:45:40

Trifid Nebula -- Discovered by Charles Messier in 1764. Charles Messier discovered this object on June 5, 1764, and described it as a cluster of stars of 8th to 9th magnitude, enveloped in nebulosity. The Trifid Nebula M20 is famous for its three-lobed appearance. This may have caused William Herschel, who normally carefully avoided to number Messier's objects in his catalog, to assign...

Triangulum Galaxy
2004-10-19 04:45:40

Triangulum Galaxy -- The Triangulum Galaxy, Messier object M33, is a spiral galaxy of type Sc located in the constellation Triangulum. Triangulum is small relative to its larger neighbors such as the Milky Way and Andromeda Galaxy, but is about average compared to most spiral galaxies in the universe. Triangulum is a member of the Local Group of galaxies and may be a gravitationally...

Tau Ceti
2004-10-19 04:45:40

Tau Ceti -- Tau Ceti is a star commonly used by science fiction authors since it is similar to the Sun, being of similar mass and similar spectral type as well as being relatively close to us. However, Tau Ceti is a "metal-deficient" star and therefore extremely unlikely to have rocky planets around it. It can be seen with the unaided eye as a faint star in the constellation of Cetus....

Sunflower Galaxy M63
2004-10-19 04:45:40

Sunflower Galaxy (M63) -- Discovered 1779 by Pierre Mchain. M63 was the very first discovery of a Deep Sky object by Messier's friend, Pierre Mchain, who caught it up on June 14, 1779. On the same day, Charles Messier included it in his catalog. The Sunflower galaxy M63 is one of the early recognized spiral galaxies, listed by Lord Rosse as one of 14 "spiral nebulae" discovered to 1850....

Sombrero Galaxy
2004-10-19 04:45:40

Sombrero Galaxy -- Discovered by Pierre Mchain or Charles Messier in 1781. M104 is numerically the first object of the catalog which was not included in Messier's originally published catalog. However, Charles Messier added it by hand to his personal copy on May 11, 1781, and described it as a "very faint nebula." It was Camille Flammarion who found that its position coincided with...

2004-10-19 04:45:40

Sirius -- Sirius (α Canis Major, also known as the Dog Star) is the brightest star (-1.46m) in the night sky and can be seen from every inhabited region of the Earth's surface. At a distance of 8.6 light years, Sirius is also one of the nearest stars to Earth. It is a main sequence star of spectral type A0 or A1 and has a mass about 2.4 times that of the Sun. Sirius has a white dwarf...

Seyferts Sextet
2004-10-19 04:45:40

Seyfert's Sextet -- Seyfert's Sextet is a group of galaxies in which gravitational forces are exerted between its members. The galaxies are so tightly packed together that gravitational forces are beginning to rip stars from them and distort their shapes. Those same gravitational forces eventually could bring the galaxies together to form one large galaxy. The name of this grouping,...

Saturn Nebula
2004-10-19 04:45:40

Saturn Nebula -- The layers of the Saturn Nebula give a complex picture of how this planetary nebula was created. The above picture, taken in April 1996 and released last week, allows a better understanding of the mysterious process that transformed a low-mass star into a white dwarf star. A computer model indicates that the central star of NGC 7009 first expelled the green gas that now...

Rosette Nebula
2004-10-19 04:45:40

Rosette Nebula -- Discovered by John Flamsteed about 1690. The Rosetta Nebula is a vast cloud of dust and gas, extending over an area of more than 1 degree across, or about 5 times the area covered by the full moon. Its parts have been assigned different NGC numbers: 2237, 2238, 2239, and 2246. Within the nebula, open star cluster NGC 2244 is situated, consisted of the young stars which...

Word of the Day
  • A poem in which the author retracts something said in an earlier poem.
The word 'palinode' comes from Greek roots meaning 'again' and 'song'.