Download a space smile - Physique chimie Dijon

Baccalauréat général
Épreuve spécifique européen anglais/sciences physiques
Session de juin 2015
Partie du programme concernée : Mécanique
A SPACE SMILE
Article taken from the NPR website on February 11, 2015
http://www.npr.org/blogs/thetwo-way/2015/02/11/385466165/from-the-cold-depths-of-spacea-smile-emerges
jpl.nasa.gov
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Space, you may have heard, can be a cold and lonely place. But the NASA/ESA Hubble
telescope has identified a particularly well-adjusted corner of space — or at least that's what
a recent image suggests, with the help of an effect called an Einstein Ring. In the Hubble
image of galaxy cluster SDSS J1038+4849, two bright galaxies resemble eyes, NASA says,
"and the misleading smile lines are actually arcs caused by an effect known as strong
gravitational lensing. "The striking photo drew our attention to a recent posting by the space
agency, in which we learned: "Galaxy clusters are the most massive structures in the
Universe and exert such a powerful gravitational pull that they warp the spacetime around
them and act as cosmic lenses which can magnify, distort and bend the light behind them.
This phenomenon, crucial to many of Hubble's discoveries, can be explained by Einstein's
theory of general relativity.
"In this special case of gravitational lensing, a ring — known as an Einstein Ring — is
produced from this bending of light, a consequence of the exact and symmetrical alignment
of the source, lens and observer and resulting in the ring-like structure we see here."
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QUESTIONS:
1) Present the text and sum it up in your own words.
2) With the help of Newton’s universal law of gravitation, explain why massive structures in
the Universe “exert such a powerful gravitational pull that they act as cosmic lenses”.
3) What other weird natural phenomena are you able to explain? (rainbows, circle sea waves
in a harbor).
4) Explain why Hubble telescope can’t take pictures from the surface of the Earth.
5) What did you enjoy the most studying in your Physics or Chemistry class this year?