AstroTalk Episode October 5, 2017

NASA’s Webb Telescope to Witness Galactic Infancy

3:12pm - 3:33pm

NASA's James Webb Space Telescope (JWST or JW) (long overdue for its launch, by the way) has a mission to look at the universe's first galaxies and stars. JW will focus on the Hubble Ultra-Deep Field (HUDF) and the Great Observatories Origins Deep Survey (GOODS). HUDF is a photo (photo?) of a tiny patch of sky that contains 10,000 or so galaxies. The galaxy are so faint, and so old, so it is hoped JW will reveal info on the temperature, mass and composition of the galaxies, through spectroscopic studies. Scientists then hope to determine, or to see, how gas was transformed into stars in the first galaxies, and how super-massive black holes in the galaxies formed. MIRI, Webb's mid-infrared instrument, and NIRCam, Webb's near infrared camera, will be the main instruments used. Webb will be able to see objects with 8 times more spatial resolution, and objects that are 250 times fainter, than the Spitzer Space Telescope could see. Webb will also see things in a different spatial band than Hubble did, so Webb will improve on all previous instruments. And Webb will be able to see with twice the spatial resolution, and at 50 times fainter, than Hubble can. The universe is expanding, so light from distant galaxies (that are moving away from us) are red-shifted. The galaxies that are farthest away have their light red-shifted in the infrared and mid-infrared bands. Webb will be ideally suited to image this light. This will make Webb ideal for looking at the early universe. Says Pablo Pérez-González, from tbe Complutense University of Madrid in Spain: “When you build an observatory with unprecedented capabilities, most probably the most interesting results will not be those that you can expect or predict, but those that no one can imagine.”

For more information about Webb telescope, visit: or

For more information about Hubble telescope, visit:

For more information about Spitzer telescope, visit:

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