Posted by Megan DeCesar on July 17, 2014
Dr. Laleh Sadeghian discussed evidence for the existence of Dark Matter. About one quarter of the universe is composed of this mysterious matter; we cannot see or touch it, but its gravity is responsible for the large scale structure we observe in the universe today. Its presence is inferred from the way its gravity alters the expected rotational behavior of galaxies, bends and magnifies light from background galaxies (gravitational lensing), and traverses merging galaxies more quickly than does regular matter (as in the Bullet Cluster). Dark Matter is not to be confused with Dark Energy, which is even more mysterious than the former; while Dark Matter gravitates, Dark Energy is responsible for the accelerated expansion of our universe.
Dr. Astrid Lamberts demonstrated that astronomers are really detectives — they piece together theoretical physics with observational evidence to determine the origins of the beautiful clouds of gas and dust we see scattered throughout our Milky Way galaxy as well as in other galaxies throughout the universe. She showed the group how to differentiate between planetary nebulae, which are the remnants of low-mass stars like our Sun and which contain a white dwarf at their core, and supernova remnants, which remain after a high-mass star explodes and leaves behind a neutron star or a black hole. The audience was tested at the end, and did quite well in identifying the objects correctly!
There are more AstroBreak public lectures to come in August. Check the website for details on the AstroBreak series, as well as other planetarium shows, lecture series, and stargazing nights. Come join us as we continue to explore the universe together!