![]() Can you see anything between us and the nebula in some cases. ![]() How do the members of your group think astronomers are able to estimate the distances of such nebulae in our own Galaxy? (Hint: Look at the images.How big are the nebulae you see in the images? Are there any clues either in the images or in the captions? Are the clouds they are part of significantly bigger than the nebulae we can see? Why? Suggest some ways that we can determine the sizes of nebulae. Your group members should look through the pictures in this chapter.For example, would it have presented a problem for early navigators? Have your group discuss how this would have affected the development of civilization on Earth. Suppose that instead it were located in a dense cloud 20 light-years in diameter that dimmed the visible light from stars lying outside it by a factor of 100. The Sun is located in a region where the density of interstellar matter is low. ![]() (The Wikipedia list does something similar: en./wiki/List_o.ssier_objects.) Astronomer Fred Espenak provides the full catalog, with information and images. Messier Catalog of Nebulae, Clusters, and Galaxies. Interstellar Medium Online Tutorial: Nontechnical introduction to the interstellar medium (ISM) and how we study it by the University of New Hampshire astronomy department. Click on any of the beautiful images in this collection, and you are taken to a page with more information while looking at these images, you may also want to browse through the slide sequence on the meaning of colors in the Hubble pictures ( ). Hubble Space Telescope Images of Nebulae. A smart-phone app for turning your phone into a cosmic-ray detector. NASA’s learning site explains about the history and modern understanding of cosmic rays.ĭECO. E., Biographical Memoir: Cosmicopia: /cosmic.html. The Herschel discovery was made in 2010.\)īarnard, E. This image was first published on the Hubble site in March 2000. This is the signature of a ‘reflection nebula’ – this one is known as NGC 1999. This bright material in the area pictured here is only visible because of the light from the star it does not emit any visible light of its own. The star is so young that it is still surrounded by a cloud of material left over from its formation. It appears white owing to its high surface temperature of about 10 000✬ – nearly twice that of the Sun. The bright star seen here is V380 Orionis, a young star 3.5 times the mass of our own Sun. ![]() The powerful radiation from a nearby mature star may also have helped to clear the hole. In general, such globules are known to be small cocoons of forming stars, but thanks to ESA’s Herschel Space Observatory, which would have been able to see any hints of star formation at infrared wavelengths but did not, along with ground-based observations, it turned out to be a truly empty patch of sky.Īstronomers think that is was formed when jets of gas from some of the young stars in the wider region punctured the sheet of dust and gas that forms the surrounding nebula. When the dark patch was first imaged, it was assumed to be a very cold, dense cloud of gas and dust, so thick as to be totally opaque in visible light, and blocking all light behind it. While the ‘fog’ is dust and gas lit up by the star, the ‘hole’ really is an empty patch of sky. This spooky sight, imaged by the NASA/ESA Hubble Space Telescope, resembles fog lit by a streetlamp swirling around a curiously shaped hole – and there is some truth in that.
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