Astronomer Biography Sources - Henrietta Leavitt

"Henrietta Leavitt." PBS. PBS, 1998. Web. <http://www.pbs.org/wgbh/aso/databank/entries/baleav.html>.

"1912: Henrietta Leavitt Discovers the Distance Key." Everyday Cosmology. Observatories of the Carnegie Institution for Science, n.d. Web. <http://cosmology.carnegiescience.edu/timeline/1912>.

"Henrietta Leavitt." Henrietta Leavitt. She Is an Astronomer, n.d. Web. <http://www.sheisanastronomer.org/index.php/history/henrietta-leavitt>.

"Henrietta Swan Leavitt - Lady of Luminosity." The Woman Astronomer. The Woman Astronomer, 01 Jan. 2008. Web. <http://www.womanastronomer.com/hleavitt.htm>.

APOD 3.5

The image below shows Asteroid Itokawa. This image was taken by the Hayabusa spacecraft launched by Japan to better understand the composition of asteroids. In addition to taking images, the spacecraft determined the mass of the asteroid by measuring the attraction of the drifting Hayabusa spacecraft. Some of the composition of the asteroid were also studied with the debris from the impact of pellets fired from Hayabusa to Itokawa. The mysterious surface of the asteroid is astoundingly devoid of craters.One hypothesis to explain this oddity is that Itokawa is simply a floating mass of rock and ice chunks loosely held together by the weak gravitational force. If craters ever formed, the rocks and ice would merely settle in those places covering up the craters. Upon further research, astronomers discovered that one part of the interior of the asteroid Itokawa has a much higher average density than the other part.

APOD 3.4

The image below is of Herbig-Haro object 24 taken by the Hubble Space Telescope in infrared light. Herbig-Haro objects are small patches of nebulosity associated with newly born stars. They are formed when thin jets of gas ejected by younger stars collide with clouds of dust and gas. Herbig-Haro objects are everywhere in star-forming regions and many form aorund a single star. Because of the rarity of them, astronomers estimate they only last a few thousand years. The star forming region is located 1,500 light years away from Earth in the Orion B molecular cloud complex. The jet in HH24 contains electrons and protons moving at hundreds of kilometers per second and it is studied to better understand young stellar objects (stars in the earliest stages of development). The dust and gas that encircles these baby stars often contribute to the formation of powerful jets.