March 25, 2017

AstroEvent of the Week: 26 August – 1 September: Spy the Core of our Galaxy!

Galactic Center.

Looking South, About an hour after local Sunset.

(Credit: Stellarium and Photoshop). 

Now for an unorthodox challege; a chance to locate something that may be visually unassuming, but very significant.

   As summer winds down, the Milky Way vaults high in the evening sky. As viewed from Northern hemisphere mid-latitudes, the core bulge sits just above the southern horizon. Nestled in this bulge is something very special; the very core of our galaxy. Where you equipped with radio wavelength vision, (A very weird eye, indeed!) you would see an intense radio source; known as Sagittarius A* (Pronounced A Star) this is an estimated four million solar mass black hole that lurks at the core of our galaxy. It’s very much a forest through the trees situation; at visible wavelengths, the brilliant core is obscured by thick dust. Located about 26,000 light years distant, the point of no return boundary would fit within the orbit of Mercury!   

   The coordinates of the Galactic Center of our galaxy are as follows: Right Ascension: 17h45m40.04s, Declination: -29 degrees 00’28.1″, right on the Sagittarius/Ophiuchus border. Visually, the area is littered with dark nebulae and clusters, but the monster that it hides is indeed mind blowing!

   The Astro-word of the week is Black Hole. A black hole is an object that is massive enough that the escape velocity exceeds that of light beyond a certain boundary, known as a Schwarzschild radius. They come in three flavors: mini-black holes, thought to be created directly after the birth of the universe (and yet to be directly observed!), stellar mass black holes, formed from a collapsed star about ten times the mass of our sun, and super massive black holes in the cores of galaxies, millions of times more massive than our sun. For a semi-mind blowing animation of stars at the core of our own galaxy, click here.


  1. [...] but also in terms of time. The stars in the Milky Way galaxy, for example, are swirling around the galactic core to the tune of one orbit every quarter of a billion years – but the constellations you see from you [...]

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