Einstein Cross

While gravitationally lensed light sources are often shaped into an Einstein ring, due to the elongated shape of the lensing galaxy and the quasar being off-centre, the images form a peculiar cross-shape instead.

Other "Einstein crosses" have been discovered.

Details

The quasar's redshift indicates that it is located about 8 billion light years from Earth, while the lensing galaxy is at a distance of 400 million light years. The apparent dimensions of the entire foreground galaxy are 0.87 × 0.34 arcminutes, while the apparent dimension of the cross in its centre accounts for only 1.6 × 1.6 arcseconds.

The Einstein Cross can be found in Pegasus at 22^h 40^m 30.3^s, +3° 21′ 31″.

Amateur astronomers are able to see some of the cross using telescopes; however, it requires extremely dark skies and telescope mirrors with diameters of 18 inches (46 cm) or greater.

The individual images are labelled A through D (i.e. QSO 2237+0305 A), the lensing galaxy is sometimes referred to as QSO 2237+0305 G.