Galileo drew the stars using four different sizes to distinguish their different brightnesses, and he published his findings in 1610. Today, spacecraft and orbiting telescopes join ground-based observers to learn more about our galaxy.
Transcript:Jane Houston Jones: What's Up for July. Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in Pasadena, California. 2009 is International Year of Astronomy, and each month this year we're showcasing a great celestial object. This month it's our Milky Way galaxy.
Title: Milky Way seen from desert
Jones: Galileo aimed his telescope towards some of the fuzzy patches of our galaxy and discovered they were made of stars. Using Ptolemy's second-century catalog of stars as a starting point...
Title: Book published by Galileo
Jones: ...he observed several well-known star clusters, like the Beehive Cluster and the Pleiades. Ptolemy had identified the six brightest stars in the Pleiades, but Galileo saw 36 stars through his telescope.
Title: Galileo's drawing of the Pleiades
Jones: He drew the stars using four different sizes to distinguish their different brightnesses, and he published his findings in 1610.
Title: Milky Way sketch by William Herschel (1785)
Jones: Through the next two centuries, astronomers used bigger and bigger telescopes...
Title: Milky Way sketch by Otto Boeddicker (1884-1889)
Jones: ...to study and map the Milky Way galaxy.
Title: Milky Way sketch by Sidney Waters (1873)
Jones: They observed nebulae, clusters and even areas where no stars could be seen. Today, spacecraft and orbiting telescopes...
Title: Herschel Space Observatory
Jones: ...join ground-based observers to learn more about our galaxy. ESA's recently-launched Herschel mission will explore the earliest stages of star and galaxy birth in the universe and will help answer questions about how our own Sun and Milky Way galaxy came to be.
Title: Spitzer Space Telescope
Jones: The Spitzer Space Telescope...
Title: Spitzer's infrared view of Milky Way
Jones: ...created the most detailed infrared picture of our galaxy ever made.
Title: Chandra X-ray Observatory
Jones: And Chandra's images of the central region
Title: Chandra's X-ray view of Milky Way
Jones: ...reveal white dwarf and neutron stars and black holes in a fog of hot gas.
From a dark sky you'll see the Milky Way rising in the East and spanning the sky from north to south after 10 p.m. local time.
Back in our own solar system, look for Saturn near the western horizon. And look for Jupiter rising in the east about 10 o'clock as the Milky Way spans the sky.
Title: To learn more about NASA's missions: www.nasa.gov
Jones: You can learn all about NASA's missions at www.nasa.gov
Title: Thanks to the following for submitting images: Anthony Ayiomamitis, Dan Durisco, Jeff Hapeman, Morris Jones.
Jones: That's all for this month. I'm Jane Houston Jones.
Title: NASA Jet Propulsion Laboratory, California Institute of Technology