Poster’s Note: The text for this month’s installment from Dee Sharples, “The Sky In September 2024,” is provided below. Those wishing to listen to the article can click on the audio link below.
September offers observers comfortable temperatures and earlier darkness as the Earth continues its journey around the sun. September 22nd at 8:44 a.m. marks the autumn equinox, the day the sun crosses the equator from the Northern to the Southern hemisphere. The hours of daylight and darkness are almost equal with days growing shorter and nights longer.
The constellation Sagittarius the Archer dominates the southern sky around 9:00 p.m. this month. It lies low near the horizon and some of its brightest stars form a shape which resembles a teapot tipping to the right. What looks like steam from the teapot rising overhead is actually the Milky Way, the galaxy where our solar system and Earth reside. Our galaxy is estimated to be made up of approximately 100 billion stars which form a large disk. The Milky Way is only one of about 200 billion galaxies in our universe and new research shows that this estimate is likely too low.
The accompanying image, called the Hubble eXtreme Deep Field (XDF), combines Hubble observations taken over the past decade of a small patch of sky in the constellation of Fornax. With a total of over two million seconds of exposure time, it is the deepest image of the Universe ever made, combining data from previous images including the Hubble Ultra Deep Field (taken in 2002 and 2003) and Hubble Ultra Deep Field Infrared (2009).
The image covers an area less than a tenth of the width of the full Moon, making it just a 30 millionth of the whole sky. Yet even in this tiny fraction of the sky, the long exposure reveals about 5500 galaxies, some of them so distant that we see them when the Universe was less than 5% of its current age.
The Hubble eXtreme Deep Field image contains several of the most distant objects ever identified.
Credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team
The beauty of the night sky and the enormity of our universe never ceases to amaze!
