The Einstein Cross & Gravitational Lensing

The Einstein Cross & Gravitational Lensing

“You cannot look OUT into space without looking BACK into time.” – Carl Sagan
Gravitational Lensing & The Einstein Cross

Photo Credit: NASA and the Hubble Space Telescope (links below)

What looks like the bottom of some sci-fi alien spacecraft, this scene is actually the phenomenon predicted by Albert Einstein known as Gravitational Lensing. Let me explain what’s going on here….

In the center of this image is a dim ball of light, that light is the core of a galaxy known as Huchra’s Lens, PGC69457 or ZW 2237+30 and the said galaxy lies a mind boggling 400 million light years distant in the constellation Pegasus. Now, the four bright points of light that appear to be surrounding the center of the galaxy are actually a Quasar. That’s right….one single Quasar named Q 2237+30 or QSO 2237+0305 whose light has been distorted around the core of the galaxy in front of it, magnified and carried around the contour of the cores gravity and shown to us on the other side, four times.

Not only is it amazing that this even takes place but what’s more is that it acts as a massive zoom eye piece, magnifying the image about 100,000 times, almost embarrassing Hubble in its magnifying power. In fact, although as I said the overlying galaxy is a massive distance away the Quasar makes 400 million light years seem like our neighbor as the Quasar itself is 8 billion light years distant!!! That’s 8,000,000,000 light years away, try calculating that distance in miles or kilometers (1 light year = 5,874,589,152,000 mi. You can round up to 5.9 trillion miles per light year, now multiply that by 8 billion. Now you can at least begin to comprehend how truly hopeless some distances in the universe can be. You are seeing two objects here, one as it was 400 million years ago and one as it was 8 billion years ago.

NAME? : Entire Scene = Einstein Cross. Galaxy = PGC 69457 or ZW 2237+30 or Huchra’s Lens. Quasar = Q 2237+30 or QSO 2237+0305.

WHAT IS IT? : A distant Quasar being Gravitationally Lensed around an overlapping Galaxy.

HOW BIG IS IT? : Apparent dimensions on the night sky are very small, only about 1.5” x 1.5” (arcseconds).

HOW FAR AWAY IS IT? : The galaxy is about 400 million light years distant & the Quasar is about 8 billion light years distant (about 2,500,000,000 parsecs).

APPARENT MAGNITUDE? : Only about +16 so unless you are packing a massive telescope (10” or larger) you probably will not even observe this object as a point of light.

WHERE IS IT? (General): Constellation Pegasus.

WHERE IS IT? (Exact RA/DEC J2000): RA 22h 40m 30s DEC +3 21’ 30”

ESA Hubble Space Telescope Page for Einstein’s Cross: http://www.spacetelescope.org/images/potw1204a/

NASA Hubble Page for Einstein’s cross: http://hubblesite.org/newscenter/archive/releases/1990/20/image/a/

Einstein Online – Gravitational Lensing: http://www.einstein-online.info/spotlights/grav_lensing_history

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