Nik's astronomy photos: M27 Dumbell Nebula

Monday, October 15, 2007

M27 Dumbell Nebula

The dumbell nebula is one of the most spectacular planetary nebulas in my opinion. You can see two shells of expanding gas in opposite directions. All class G stars die in this manner. This is the fate of our sun as well.

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Astronomy Facts

1. Objects near the horizon are distorted the most because of the thicker air.

2. The point directly above you is called the zenith. This is where the air is the thinest and most transparent.

3. Star brightness is ranked according to magnitude (smaller numbers being brighter and larger numbers being fainter).

4. Light pollution is a phenomena caused by street lights reflecting off of our atmosphere. In urban areas light pollution causes many faint deep sky objects like our milky way galaxy and other nebulae and galaxies to fade and become invisible.

5. You can notice the earth's rotation if you point an unmotorized telescope at a celestial object.

6. Objects like pluto or the asteroids are discovered by taking photographs hours apart and then blinking them on your computer to show motion.

7. Some of the techniques used to determine distances to objects are parallax, spectroscopic parallax and Type IA supernovae.

8. Venus is one of three objects in which we can observe a complete set of phases. The others being the moon and mercury.

9. Deep sky objects like nebulae, galaxies, and globular clusters appear as faint, fuzzy objects when viewed through a telescope.

10. Unlike the human eye, a camera can capture many more photons by extending the exposure time, producing brighter, more detailed images.

11. CCDs or Charged Couple Devices are a type of digital camera without a lens which are used for astrophotography. The telescope is used as a giant telephoto lens instead.

12. The brightest nebula to hunt for (no pun intended) is the Orion nebula and the brightest galaxy is the Andromeda galaxy.

13. Gems or German Equatorial Mounts are mounts that can track celestial objects without any field rotation and are renouned for their astrophotography capability.

14. The size of a telescope is referred to as its aperture. It is measured in either inches or mm. My scope is 10" or 250 mm.

15. There are many optical designs, but most are a variation of either the reflector, refractor, or cassegrain.

16. Reflectors A.K.A. Newtonians are a type of telescope which focus light with a parabolic mirror. One drawback to newtonians is fuzzy star images. On the plus side, they are cheap to manufacture and you can purchase a large aperture.

17. Refractors are a type of telescope which focus light with an objective lens. Usually they are very small because the glass element is too expensive to manufacture. One problem with refractors is chromatic aberration (color fringing).

18. Cassegrains have long been known for their excellent optical quality. They use a series of lenses and mirrors to focus light.

19. One can detect more detail in faint objects by using averted vision, which is looking slightly away from the center. This is because rod cells are more sensitive to light and are located toward the outside of the retina. Cone cells are located toward the center of the retina for color.

20. Color is very difficult to notice in low light conditions, unless the target is very bright.

21. Relaxing the gaze makes your pupils larger and allows more light into your eye.

22. A motorized focuser can help reduce vibrations while focusing.

23. Carpeting will also dampen out vibrations when using very high magnifications.

24. High power eyepieces will give you the best views of planets while low power eyepieces will give you the best views of deep sky objects.

25. The best time to do some observing is in the winter because there is little moisture in the air for street lights to reflect off of.

Nik's astronomy photos

Monday, October 15, 2007

M27 Dumbell Nebula

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