Einstein Cross Facts for Kids

Quick facts for kids Einstein Cross

Observation data (Epoch J2000)
Constellation	Pegasus
Right ascension	22^h 40^m 30.3^s
Declination	+3° 21′ 31″
Redshift	1.695
Distance	8,000,000,000 ly (2,500,000,000 pc)
Type	LeQ
Apparent dimensions (V)	less than 2"
Apparent magnitude (V)	16.78
Other designations
LEDA 69457, Z 378-15
See also: Quasar, List of quasars

The Einstein Cross is an amazing sight in space. It's a quasar whose light is bent by a huge galaxy in front of it. This bending light makes the quasar look like four separate bright spots, forming a cross shape.

Imagine looking at a very bright light far away. If something really massive, like a galaxy, passes between you and that light, its gravity can act like a giant magnifying glass. This effect is called gravitational lensing.

The galaxy bending the light is named ZW 2237+030, also known as Huchra's Lens. It sits right in front of the distant quasar. Because of this, we see four images of the same quasar. There's also a fifth image right in the center, but it's usually too faint to see.

Scientists John Huchra and his team first found this system in 1985. At first, they only knew there was a quasar behind a galaxy. They figured this out by looking at their different redshifts. Redshift tells us how fast objects are moving away from us. Later, they could see the four separate images of the quasar.

Usually, when light is bent by gravity, it forms a circle called an Einstein ring. But the galaxy in front of the Einstein Cross is a bit stretched out. Also, the quasar isn't perfectly centered behind it. These reasons make the images form a unique cross shape instead of a ring.

Scientists have found other "Einstein crosses" too!

What is the Einstein Cross?
Images for kids
See also

What is the Einstein Cross?

The Einstein Cross is a special example of gravitational lensing. This happens when a huge object, like a galaxy, bends the light from an even more distant object. It's like looking through a funhouse mirror in space.

How Far Away is the Einstein Cross?

The quasar that makes up the Einstein Cross is incredibly far away. Its light has traveled for about 8 billion light-years to reach Earth. A light-year is the distance light travels in one year. That's a huge distance!

The galaxy that's bending the light is much closer. It's about 400 million light-years from Earth.

Where Can You Find the Einstein Cross?

You can find the Einstein Cross in the constellation Pegasus. Its exact location in the sky is 22^h 40^m 30.3^s, +3° 21′ 31″.

Can You See the Einstein Cross?

It's very hard to see the Einstein Cross with your own eyes. Even amateur astronomers need powerful telescopes to spot it. You would need a telescope with a mirror at least 18 inches (about 46 cm) wide. You would also need very dark skies, far away from city lights.

Naming the Images

The four bright images of the quasar are usually called A, B, C, and D. So, you might hear them called QSO 2237+0305 A, for example. The galaxy that causes the lensing is sometimes called QSO 2237+0305 G.