Seed Question: Hubble showed that the universe is expanding. What do you think the universe is doing right now?

A) Expansion is speeding up

B) Expansion is slowing down

C) Expansion is continuing at a steady rate

Exploration:

Astrophysicist Vera Rubin discovered that galaxies are spinning too fast based on the amount of ordinary mass that we think is there.

Tape in galaxy rotation curve.

By Mario De Leo - Own work, CC BY-SA 4.0

What is this invisible, unseen attracting mass?Dark Matter.

We found more of this Dark Matter through gravitational lensing.

The Composition of the Universe

In 1999, two teams of astrophysicists discovered that the expansion of the universe is _______________ . Insert expansion graphic.

By Ann Feild (STScI) - http://hubblesite.org/newscenter/archive/releases/2001/09/image/g/ OR http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=37294788

This doesn’t make sense in terms of the Dark Matter we infer is there. We need another name for the mysterious, unseen, repelling stuff. We call it Dark Energy.

What are the two scales that these dark entities act at?

Big Idea: Here is our current best breakdown for the composition of the universe:

Discussion: