NGC 604 is a H II region inside the Triangulam Galaxy. It was discovered by William Harschel on 11th Sep,1784. It is one of the largest H II regions in the Local Group of galaxies estimated distance of 2.7 million light-years it's longest diameter is roughly 1500 light-years(460 parsecs) over 40 times the size of the visible portion of the Orion Nebula. It is over 6300 times mo
re luminous than the Orion Nebula and if it were at the same distance it would out shine Venus Like all emission nebulae it's gas is ionized by a cluster of Massive stars at it's center.
This clock representation shows some of the major units of geological time and definitive events of Earth history, The Hadean eon represents the time before fossil record of life on Earth, its upper boundary is now considered as 4.0Ga. Other sub-divisions reflect the evolu
tion of life. The Archean and Proterozoic are both eons, The Palaeozoic, Mesozoic and Cenozoic are eras of the Phanerozoic eon the two million years Quaternary period. The time of recognizable humans is too small to be visible at this scale.
image credit: NASA,EST,HST, Andrew Fruchter,(STScI)and the ERO team(STScI+ST-ECF)_
NGC 2392 lies more than 2870 light year away and visible in the Constellation of Gemini._
The Eskimo Nebula(NGC 2392) ,also know as the Clownface Nebula or Caldwell 39, is a bipokar double-Shell planetary nebula. In 1787,William Harschel discovered it.
The formation resembles a person's head surrounded by a Parka hood. It is surrounded by gas that composed the other layers of a Sun-like star._
The visible inner filaments are ejected by a strong wind of particles from the central star, The outer disk,contains unusual light year long orange filaments.
so that Earth does not occult the stars which are observed continuously, and so the photometer is not influenced by stray light from Earth. This orbit avoids the gravitational perturbations and Torques inhernt in an Earth orbit, allowing for a more stable viewing platfrom.
The photometer points to a field in the Northern constellations of Cygnus, Lyra and Draco(image), which is well out of the ecliptic plane. So sunlight never enters the photometer as the spacecraft orbits the Sun,Cygnus is also a good choice to observe because it'll never be obscured by asteroid belt.
other benefit is that Keplar is pointing in the direction of the Solar system's motion around the center of the galaxy. Thus the stars which are observed by Keplar are roughly the same distance from the glactic center as the solar system and also close to the galactic plane. its important if position in the Galaxy is related to habitability as suggested by the Rare Earth hypothesis____
The photometer points to a field in the Northern constellations of Cygnus, Lyra and Draco(image), which is well out of the ecliptic plane. So sunlight never enters the photometer as the spacecraft orbits the Sun,Cygnus is also a good choice to observe because it'll never be obscured by asteroid belt.
other benefit is that Keplar is pointing in the direction of the Solar system's motion around the center of the galaxy. Thus the stars which are observed by Keplar are roughly the same distance from the glactic center as the solar system and also close to the galactic plane. its important if position in the Galaxy is related to habitability as suggested by the Rare Earth hypothesis____
Exp:what does a Coment nucleus look like?
Formed from the priomordial stuff of the solar system.It's thought to resemble a very dirty iceberg.But for active comets,telescopic images only reveal the surrounding cloud of gas n dust, the comet's coma n the characteristic cometary tails.In 1986 The ESA's Giotto encountered the necleus of Halley's comet as it approached the Sun.Data from Giotto Camera was used to generate this enhanced image of the potato shaped nucleus which measured roughly 15km across,It shows surface features on the dark nucleus against the bright background of the coma as the icy material is Vaporized by the sun's heat,Every 76yrs Halley returns to the inner solar system n each time the nucleus sheds about a 6 meter deep layer of its ice n rock into space.This debris composes Halley's tails n leaves an orbiting trail responsible for the Orionids meteor shower
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