[Gravitational lensing image on screen.]
Ms. Iteede: So you can see, the gravity of an object can bend nearby light from other objects.It’s just the bending of light from objects we can see.
Zadri: But Ms. Iteede? How does gravitational lensing tell us anything about dark matter?
Epo: I can answer this question, Ms. Iteede.
Ms. Iteede: Wonderful. Go ahead Epo.
Epo: The gravitation lensing gives the total mass of the lensing matter, but the visible mass is much less than that.
Alkina: So the difference is dark matter!
Ms. Iteede: Correct, Alkina. Where we see these distant objects indicate that there is far more mass in the foreground lens that we can see.
Ms. Iteede: That’s all for today. Remember your permission slips for the museum field trip.
In human speak please!
Gravitational lensing helps astronomers understand how much dark matter a galaxy or galaxy cluster contains as well as how dark matter is distributed in and around the lensing object. However, gravitational lensing is not just used for understanding dark matter. The lens often amplifies the light of the distant object, such that without the lens we would not be able to detect it. This makes gravitational lenses powerful tools in looking even further back into the early, and distant, Universe. Lensing can also be used to measure distances to objects.