Phil PlaitA new paper just published in the prestigious Astrophysical Journal makes a stunning claim: There are 10 times as many galaxies in the Universe as we previously thought. At least. The total number comes in at about 2 trillion of them. Now, let me be clear. What the astronomers did was look at extremely deep images of the Universe taken in surveys, for example the Hubble Ultra Deep Field. That’s a lot of galaxies. Surveys like the UDF are limited. The astronomers who did this research had an interesting problem. The answer is two-fold. Those numbers change with distance. At the same time, these faint galaxies are easier to see close to us, and harder farther away. They calculated this for all kinds of galaxies, right down to really small ones with about a million times the mass of the Sun. They can then combine these two pieces of information: How many faint galaxies there are near us and how bright they are, with how many galaxies of a given mass are in a volume of space. NASA,ESA, H.
Engineering a BridgeThis lesson will involve your students in geometry and measurement as they work as civil engineers to design and build their own bridge. OBJECTIVE Students will be able to: Identify how geometry affects bridge design and function and apply that knowledge to the design and construction of a bridge. MATERIALS Elmer's Foam board, Popsicle sticks, pipe cleaners, bendable rods, Elmer's Glue All, paper, pushpins, weightsEngineering a Bridge PDF SET UP AND PREPAREContent Introduction When engineers design a bridge, they must consider how the bridge will be used, how long and wide it should be, and how much weight it has to hold. There are four main types of bridges: Beam bridges are made of horizontal beams supported by piers at each end.Truss bridges are a combination of triangles made of steel. Essential Questions Use these essential questions to help guide students' thinking: How does geometry help engineers build bridges? Craft Component: Bridge Engineering (20 minutes)
Dr. Michio KakuExploratorium: the museum of science, art and human perception