A Basic Guide to How the Cosmos Works (and what do all those funny abbreviations mean?)

1. A Basic Guide to How the Cosmos Works (and what do all those funny abbreviations mean?) Bryan P Shumaker NOMAC

2. The Solar System • Our sun is the center of the solar system . It is about 93 million miles away. • This distance is called an “A.U.” (Astronomical Unit) and is often used as a unit of measurement • The planets rotate around the sun, mostly in the same plane and all in the same direction • Mercury, Venus, Earth, and Mars are considered the rocky planets

3. The Solar System • The asteroid belt is material left over when the solar system first formed and unable to form a planet due to the strong gravitational influence of Jupiter • Jupiter and Saturn are considered the gas giants • Uranus and Neptune are called the ice giants • Beyond Uranus is a vast cloud of objects (including Pluto) which make up the Kuiper Belt

4. The Solar System

5. The Solar System • Beyond the Kuiper Belt is a vast shell of icy bodies and proto comets which make up the Oort Cloud. • This extends out about one light year from the Sun

6. The Solar System

7. Distances • Because of the enormous distances in space, we refer to the distance as how far light will travel in a set period of time. Light travels at 300 million m/sec., or about 186,000 miles/sec. • The distance from the Sun to the Earth is about 8 light minutes • The distance from the Sun to Neptune is about 4.5 billion miles, or 30.1 AU, or about 4.2 light hours!

8. Solar System • The distance to the probable edge of our solar system is about 1.5 light years • The NEAREST star is just over 4 light years away • How do we measure distances to such far away objects?

9. Distance Measurement • One way to measure distance is by carefully measuring the change in angle to an object from two different points in space and use basic trigonometry. We take a picture and compare it with an identical picture taken 6 months later. The slight shift is measured in arc seconds (60 of which make 1 degree). This change in view, or parallax, is then used to calculate how far away an object is. The moon is about 0.5 degrees wide.

10. Distance Measurement • A measurement of one arc second’s worth of parallax change is called a “parsec” and works out to 3.26 light years • This system works well up to about 30 -40 light years—it becomes increasingly difficult to measure such tiny shifts beyond this distance

11. Distance Measurement • Cepheid Variables---These are a group of stars that vary in their brightness on a very consistent, periodic schedule. This variability is directly proportional to their luminosity. If you can measure the brightness and compare it to a star of known brightness, you can determine how far away that star is. • Okay for distances up to several million light years (need to be able to see individual stars of the distant galaxy)

12. Distance Measurement • Doppler shifting (Red Shift) • Light moving toward us is compressed and on a spectrograph (fancy prism), the light is shifted slightly towards the blue. If moving away, the light is shifted towards the red end of the spectrum

13. Distance Measurement

14. Distance Measurement • Everything in space is basically accelerating away from each other. The farther away an object is, the faster it is moving. This is a constant, uniform increase in both speed and distance, and is called the Hubble constant. • By measuring the amount of red shift, we are able to determine how far and how fast an object is moving away and at what distance. • At present , we can see objects almost 12.5 BILLION light years away—almost the time when it all began—the Big Bang.

15. Interstellar Space • This is the space between the stars and objects in our own galaxy • Our galaxy measures about 120,000 light years in diameter and contains approx. 300 -600 billion stars! We are about 60,000 light years from the galactic core • Our galaxy, which we call the Milky Way, is part of a larger cluster of galaxies called the Local Group

16. Seemingly infinite Space!

24. Common Terms • Cardinal Directions -- North, South, East, West

25. Common Terms • Altitude (Alt) -- The number of degrees an object is above the horizon. Ninety degrees is straight up • Azimuth (Az) -- The point where the object is closest to the horizon and is measured in degrees in a circle along the horizon, starting with North ( 0 or 360)

26. Common Terms • Celestial Equator-- Located on the Earth’s equator, but projected into space • Declination (Dec) -- The number of degrees the object observed is north or south of the Celestial Equator • Right Ascension (RA)-- Measured in hours along the Celestial Equator. It runs from 0 hours to 24 hours

27. Common Terms • Ecliptic—The plane of the Earth’s orbit around the Sun. This is about 23 degrees north of the true equator since the Earth is tilted about this amount off the vertical • Zenith—Directly above the observer • Meridian– An imaginary line connecting the north and south poles running directly overhead

28. Telescope Type Review • Refractor

29. Telescope Type Review • Reflector

30. Telescope Type Review • Cassegrain (multiple variants of this)

31. Eyepieces • The larger the size in mm, the less the magnification. A 24mm eyepiece gives less magnification than a 9mm one • Divide the focal length of the telescope by the eyepiece size=magnification • Multiple types—Orthos, Kellners, Plossls, Erfles, RKEs, Radians—the list goes on and on! • The cost varies from $30 to $800 PER EYEPIECE

32. Eyepieces

33. Space Object Abbrev. • Many objects in space are described by a name, a number, or a combination of both. Some of the more well known ones have popular names used as well • M objects--named for Charles Messier, 18th century French comet hunter

34. Space Object Abbrev. • M1 through M110—A list of popular and relatively easy to find objects which include galaxies, open star clusters, globular clusters, planetary nebulae • QUICK NOTE—a globular cluster is a tight ball of stars which may contain up to 100,000 stars densely packed in a few light years. They are located above and below the galactic plane and are very old

35. Space Object Abbrev. • QUICK NOTE– A planetary nebula is actually a star that has blown off its outer layers as part of its death process • Globular cluster Planetary neb.

36. Space Object Abbrev. • Open Cluster– A group of stars that formed at about the same time and location and are loosely bound together by gravity • Double Star --The stars have to be physically interacting with each other and not just a line of sight chance arrangement • Nebula -- A collection of gas and or dust. Often they are large clouds of dust, gas and are stellar nurseries

37. Open Cluster

38. Double Star

39. Nebula

40. Nebula (M42)

41. Nebula

42. Nebula (Barnard 33 or IC 44)

43. Space Object Abbrev. • NGC-- stands for New Galactic Catalog • Arp -- named after Alton Arp,; describes irreg. galaxies • Greek letters used to designate prominent stars • HIP-- from the Hipparchos star catalog • B objects-- named after Barnard, describes clouds of dark gas and dust • Caldwell -- lists of certain galaxies • IC -- describes bright, glowing clouds of gas and dust

44. Space Object Abbrev. • There are several other specialized lists and types of objects • Almost all the objects viewable to amateur astronomers are in one of these lists and/or catalogs • For a great view of the different types of objects and categories, visit http://www.utahskies.org/deepskyIndex.shtml • Visit www.nomac.net for this link and many other useful ones

45. CLEAR SKIES!