Event Date: September 20th
Time: 5:30 AM
Brief
Yesterday I showed Leo Minor zoomed in with some stars labeled along with those of the small stick-figure, which doesn't seem to represent a lion at all-- compared to the big Lion constellation anyway. Also, this is a part of the sky where we are looking close to perpendicular out of our Milky Way, so the density of stars per arc-second of sky is smaller. However, we can still try to find some very deep sky objects in this area: mainly galaxies, yet also a couple of nebulae nearer to the Big Bear. Zooming out, I labeled a few of these shown below, near the constellations that I talked about in yesterday's entry. As seen, there are many others in the east-northeast at this time of day and year as well, while still dark enough.
Time: 5:30 AM
Brief
Yesterday I showed Leo Minor zoomed in with some stars labeled along with those of the small stick-figure, which doesn't seem to represent a lion at all-- compared to the big Lion constellation anyway. Also, this is a part of the sky where we are looking close to perpendicular out of our Milky Way, so the density of stars per arc-second of sky is smaller. However, we can still try to find some very deep sky objects in this area: mainly galaxies, yet also a couple of nebulae nearer to the Big Bear. Zooming out, I labeled a few of these shown below, near the constellations that I talked about in yesterday's entry. As seen, there are many others in the east-northeast at this time of day and year as well, while still dark enough.
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| click on image to enlarge: courtesy of Starry Night Pro Plus, version 6.4.3, by Simulation Curriculum Corp. |
Detailed
Many of these, including a bright one near the Big Bear's tail (Dipper's handle), are emission or planetary nebulae. The emission nebulae, as viewed with small telescopes mainly have a grey appearance. Other times, as seen with a more powerful telescope, a red appearance, as hydrogen gas becomes heated by young stars which are very hot already. When the gas becomes heated to about 10,000 kelvin, the red (or some other colors for certain nebulae such as the Orion) starts to show. As for the planetary nebulae, they are seen for only a short time compared to the emission ones: the gas shell becomes fainter as it grows out further from the central (dying) star, blending in with surrounding interstellar medium. The time it takes for this to happen is about 10,000 years. Tomorrow, I will show one of the most popular planetary nebulae in our sky, which can be seen easily in a dark sky with even portable telescopes. Do you have any idea which this is? Hint: it is barely within the boundaries of the Summer Triangle, made up of Vega, Deneb and Altair.
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