Strong Lensing

Effect due to gravitational bending of light by mass concentrations which results in (1) the strong distortion of background galaxyConcentration of 10⁶ to 10¹² stars, dust and gas, that are gravitationally bound. Our galaxy contains ~2 × 10¹¹ stars. There are four main types of galaxies: • Elliptical
• Lenticular
• Spiral
• Irregular
Click on Term to Read More images (arcs) behind some massive foreground galaxy clusters, and (2) multiple images of the same background quasar behind a foreground galaxy. Over 50 lensed quasi-stellar objects are known.

Image source: http://www.centauri-dreams.org/wp-content/uploads/2006/05/lensed_quasar_2.jpg.