astronomypictureoftheday: The Orion BulletsCosmic bullets pierce the outskirts of the Orion Nebula some 1500 light-years distant in this sharp infrared close-up. Blasted out by energetic massive star formation the bullets, relatively dense, hot gas clouds about ten times the size of Pluto’s orbit, are blue in the false color image. Glowing with the light of ionized iron atoms they travel at speeds of hundreds of kilometers per second, their passage traced by yellowish trails of the nebula’s shock-heated hydrogen gas. The cone-shaped wakes are up to a fifth of a light-year long. The detailed image was created using the 8.1 meter Gemini South telescope in Chile with a newly commisioned adaptive optics system (GeMS). Achieving a larger field of view than previous generation adaptive optics, GeMS uses five laser generated guide stars to help compensate for the blurring effects of planet Earth’s atmosphere. Image Credit: GeMS/GSAOI Team, Gemini Observatory, AURA Processing: Rodrigo Carrasco (Gemini Obs.), Travis Rector (Univ. Alaska Anchorage)
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astronomypictureoftheday:

The Orion Bullets

Cosmic bullets pierce the outskirts of the Orion Nebula some 1500 light-years distant in this sharp infrared close-up. Blasted out by energetic massive star formation the bullets, relatively dense, hot gas clouds about ten times the size of Pluto’s orbit, are blue in the false color image. Glowing with the light of ionized iron atoms they travel at speeds of hundreds of kilometers per second, their passage traced by yellowish trails of the nebula’s shock-heated hydrogen gas. The cone-shaped wakes are up to a fifth of a light-year long. The detailed image was created using the 8.1 meter Gemini South telescope in Chile with a newly commisioned adaptive optics system (GeMS). Achieving a larger field of view than previous generation adaptive optics, GeMS uses five laser generated guide stars to help compensate for the blurring effects of planet Earth’s atmosphere.

Image Credit: GeMS/GSAOI Team, Gemini Observatory, AURA Processing: Rodrigo Carrasco (Gemini Obs.), Travis Rector (Univ. Alaska Anchorage)

So recently, I’ve been reading a lot of the wonderful Alastair Reynolds’ Revelation Space sci fi series, and as a result, I’ve spent a lot of time thinking about something that (depending on how anxious you are as a person) may well leave you in cold sweats. In around 4 billion years’ time, the Milky Way and Andromeda galaxies will collide. Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda’s transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy the solar system will be swept out three times farther from the galactic core than it is currently located. They also predict a 12% chance that the Solar System will be ejected from the new galaxy some time during the collision. Such an event would have no adverse effect on the system and chances of any sort of disturbance to the Sun or planets themselves may be remote. On the bright side (I suppose) is this: Without intervention, by the time that the two galaxies collide, the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life, which is currently estimated to occur in about 1.4 billion years due to gradually increasing luminosity of the Sun. I still like the idea of the solar system being shot off out into the space between galaxies though.  Just imagine what it’d be like to live on a planet so much further out from all the stars we see in the night sky.  
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So recently, I’ve been reading a lot of the wonderful Alastair Reynolds’ Revelation Space sci fi series, and as a result, I’ve spent a lot of time thinking about something that (depending on how anxious you are as a person) may well leave you in cold sweats.

In around 4 billion years’ time, the Milky Way and Andromeda galaxies will collide.

Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda’s transverse velocity. Based on current calculations they predict a 50% chance that in a merged galaxy the solar system will be swept out three times farther from the galactic core than it is currently located. They also predict a 12% chance that the Solar System will be ejected from the new galaxy some time during the collision. Such an event would have no adverse effect on the system and chances of any sort of disturbance to the Sun or planets themselves may be remote.

On the bright side (I suppose) is this:

Without intervention, by the time that the two galaxies collide, the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life, which is currently estimated to occur in about 1.4 billion years due to gradually increasing luminosity of the Sun.

I still like the idea of the solar system being shot off out into the space between galaxies though.  Just imagine what it’d be like to live on a planet so much further out from all the stars we see in the night sky.  

Source: Wikipedia

Carl Sagan was right, you know.  Space is badass.  (That may or may not be a paraphrase.)  From the Wikipedia article on Sagittarius A*, which we assume is a supermassive black hole at the centre of our galaxy: Astronomers are confident that these observations of Sagittarius A* provide good empirical evidence that our own Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System because: The star S2 follows an elliptical orbit with a period of 15.2 years and a pericenter (closest distance) of 17 light hours (1.8×1013 m) from the center of the central object. From the motion of star S2, the object’s mass can be estimated as 4.1 million solar masses. The radius of the central object must be significantly less than 17 light hours, because otherwise, S2 would either collide with it or be ripped apart by tidal forces. In fact, recent observations indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus’ orbit. The only known type of object which can contain 4.1 million solar masses in a volume that small is a black hole. While, strictly speaking, there are other mass configurations that would explain the measured mass and size, such an arrangement would collapse into a single supermassive black hole on a timescale much shorter than the life of the Milky Way. Seriously, how bitchin’ is that?
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Carl Sagan was right, you know.  Space is badass.  (That may or may not be a paraphrase.)  From the Wikipedia article on Sagittarius A*, which we assume is a supermassive black hole at the centre of our galaxy:

Astronomers are confident that these observations of Sagittarius A* provide good empirical evidence that our own Milky Way galaxy has a supermassive black hole at its center, 26,000 light-years from the Solar System because:

  • The star S2 follows an elliptical orbit with a period of 15.2 years and a pericenter (closest distance) of 17 light hours (1.8×1013 m) from the center of the central object.
  • From the motion of star S2, the object’s mass can be estimated as 4.1 million solar masses.
  • The radius of the central object must be significantly less than 17 light hours, because otherwise, S2 would either collide with it or be ripped apart by tidal forces. In fact, recent observations indicate that the radius is no more than 6.25 light-hours, about the diameter of Uranus’ orbit.
  • The only known type of object which can contain 4.1 million solar masses in a volume that small is a black hole.

While, strictly speaking, there are other mass configurations that would explain the measured mass and size, such an arrangement would collapse into a single supermassive black hole on a timescale much shorter than the life of the Milky Way.

Seriously, how bitchin’ is that?

Source: Wikipedia

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