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01/24/2022 – Ephemeris – The Great Orion Nebula

January 24, 2022 Comments off

This is Ephemeris for Monday, January 24th. Today the Sun will be up for 9 hours and 30 minutes, setting at 5:40, and it will rise tomorrow at 8:09. The Moon, 1 day before last quarter, will rise at 1:03 tomorrow morning.

The closest star nursery to us, places where stars are being born, is the Great Orion Nebula, 1,300 light years away. A light year is about 6 trillion miles, if you want to pace it out. It’s located in the constellation Orion’s sword that hangs below his belt. In as little as a pair of binoculars, it shines by emission and reflection of the light of a tiny clutch of four stars at its heart, which astronomers have called the Trapezium. These extremely hot young massive stars are not destined to live long. Unlike the Sun’s 10 billion year lifetime, these stars lifespans will be measured in millions of years. Yet do not mourn for them, even now stars are forming within their dusty cocoons in the nebula. The Trapezium stars’ deaths will provide heavy elements for new stars and planets.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

The lower part of Orion with the Great Orion Nebula. Created using Stellarium.

The lower part of Orion, with the Great Orion Nebula. Created using Stellarium.

The Great Orion Nebula (M42) long exposure photograph

The Great Orion Nebula (M42) long exposure photograph by Scott Anttila. Includes all the sword stars.

Inner part of the Great Orion Nebula. Image by Scott Anttila

The inner and brightest part of the Great Orion Nebula. Also, visible are the four stars of the Trapezium, whose ultraviolet emissions light up the nebula. This is pretty much one’s perception of the nebula as seen in a small telescope, except it would appear colorless. In larger telescopes, one would perceive a greenish color. The red color of hydrogen is outside our night adapted visual range. The green emission is due to mainly doubly ionized oxygen and the green emission of hydrogen. Image by Scott Anttila.

01/13/2022 – Ephemeris – The Moon, first target for a new telescope

January 13, 2022 Comments off

This is Ephemeris for Thursday, January 13th. Today the Sun will be up for 9 hours and 8 minutes, setting at 5:26, and it will rise tomorrow at 8:17. The Moon, halfway from first quarter to full, will set at 5:47 tomorrow morning.

The Moon is probably the first astronomical object owners of a new telescope look at. The first discovery is that it’s not that easy to find. Most telescopes produce an upside down or a mirror reversed image, so steering the telescope may take a bit of getting used to. The Moon is at its gibbous phase tonight, so it’s quite bright, and a lot of it doesn’t have much contrast except for the large dark gray areas, called seas. There’s no water in them, of course, but they are huge lava basins caused by large asteroid impacts in the early days of the Moon’s history. The best detail on the Moon is near the terminator, in the time before full moon, it is the sunrise line. There the shadows are longest, and the detail of craters are best seen.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Virtual Moon Atlas showing Moon for tonight

This is a great guide to the Moon called Virtual Moon Atlas for a computer, showing the Moon for any date and time. It’s a free app which runs natively on Windows, but also can run with emulators on Linux and macOS. I find it to be an amazing program. Check it out under Free Astronomical Software on the right of this page.

The other free app I use is Stellarium (See the right column). Zoom in enough, so the Moon fills the frame, and It will show labels to some of its features if clicked on.

01/07/2022 – Ephemeris – Help with your telescope tonight

January 7, 2022 Comments off

This is Ephemeris for Friday, January 7th. Today the Sun will be up for 8 hours and 59 minutes, setting at 5:19, and it will rise tomorrow at 8:19. The Moon, 2 days before first quarter, will set at 11:18 this evening.

Did you or someone in your family get a telescope for Christmas, or have one in a closet or attic because you don’t know how to put it together or how to operate it? Or maybe you are trying to figure out which one to buy. Well, tonight’s your night. The Grand Traverse Astronomical Society will host a virtual telescope clinic via Zoom starting at 8 pm. Professor Jerry Dobek of Northwestern Michigan College will demonstrate the types of telescopes and how to use them. He and other members may be able to help particular problems by seeing participants telescopes using their webcams or smartphones. This should be interesting, to say the least. Go to gtastro.org for information and a link for the meeting.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Here’s a quick guide to telescopes, how they work, and what’s important in selecting one that I wrote some time ago: Telescope Basics2.pdf

Alternately, when we get back to in-person star parties at the Northwestern Michigan College’s Joseph H. Rogers Observatory, we invite folks to bring their telescopes. Members can have a look at them at or near the end of the evening.

12/28/2021 – Ephemeris – The James Webb Telescope is on its way to L2

December 28, 2021 Comments off

This is Ephemeris for Tuesday, December 28th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:09, and it will rise tomorrow at 8:19. The Moon, 2 days past last quarter, will rise at 3:18 tomorrow morning.

The James Webb Space Telescope was launched Christmas morning and is heading out past the Moon’s orbit. It was launched from the European Space Agency’s Spaceport in Kourou, French Guiana on the northeast coast of South America, as part of their contribution to the project. It will orbit a point called Lagrange Point 2, or L2 for short, over four times the Moon’s distance in a direction opposite of the Sun. It will take the telescope 29 days to unfold itself. First order of business was to unfold the solar panels to obtain power, then to deploy its high gain antenna for communications with the Earth. Next to begin to deploy a 5 layer, tennis court sized sun shield. After that, the telescope will be unfolded.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

The last view of Webb as it separated from the Ariane 5 launch vehicle

The last view of Webb as it separated from the Ariane 5 launch vehicle. Credit: NASA.

07/19/2021 – Ephemeris – How does your telescope’s image orientation compare to how it looks to the naked-eye?

July 19, 2021 Comments off

This is Ephemeris for Monday, July 19th. Today the Sun will be up for 15 hours and 6 minutes, setting at 9:22, and it will rise tomorrow at 6:16. The Moon, 2 days past first quarter, will set at 2:35 tomorrow morning.

When you look through a telescope at the Moon, how does it look compare to how it looks to the naked-eye? Yes, it’s bigger and probably brighter. But how did its orientation change? Astronomical telescopes generally give an upside-own image, that is rotated 180 degrees. Newtonian reflector telescopes, with their eyepiece near the top of the telescope, give such an image, as do refractor telescopes where the diagonal mirror near the eyepiece is not used. When such a mirror is used a right side up, but mirror image is the result. The mirror image results when an odd number of reflections occur in the light path. Binoculars use two or four reflections. Newtonian reflectors have two reflections. It can be confusing sometimes.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hr). They may be different for your location.

Addendum

Telescope image orientations

Categories: Concepts, Observing, Telescopes Tags:

10/05/2018 – Ephemeris – All about telescopes for the gift giving season

October 5, 2018 Comments off

Ephemeris for Friday, October 5th. The Sun will rise at 7:45. It’ll be up for 11 hours and 30 minutes, setting at 7:15. The Moon, halfway from last quarter to new, will rise at 4:28 tomorrow morning.

We at the Grand Traverse Astronomical Society get asked a lot about what kind of telescope to get for their beginning astronomer, whether young or old. With the gift-giving season coming upon us, now is the time to plan ahead. This month’s meeting at 8 p.m. at the Northwestern Michigan College’s Rogers Observatory there will be several types of telescopes there, including one of mine*. There is no right telescope, but there are lots of wrong telescopes, and its not always the telescope itself, but the mounting that’s the problem. Society members will show you what the various telescopes can do, what you need, and don’t need. What’s the best telescope for what price range.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

* I’m currently suffering from a sprained wrist, so I may not be able to bring in my 11″ Dobsonian telescope, but will bring in a much smaller (3″) telescope of similar design instead.

02/02/2018 – Ephemeris – Telescope clinic rescheduled to tonight

February 2, 2018 Comments off

Ephemeris for Ground Hog Day, Friday, February 2nd. The Sun will rise at 8:00. It’ll be up for 9 hours and 52 minutes, setting at 5:52. The Moon, 2 days past full, will rise at 8:43 this evening.

If you’ve received a telescope for Christmas and are having trouble setting it up, or have an unused one in a closet, basement or attic, bring them to Northwestern Michigan College’s Rogers Observatory tonight at 8 p.m. The Grand Traverse Astronomical Society will be holding their annual telescope clinic to help you understand and use your telescope. Last month’s meeting and clinic was canceled due to the weather. The clinic will extend through the period that will be set aside for a star party if it’s clear, to test the telescopes and show the owners how to use them. Like anything telescopes take some time to learn how to use them and find celestial objects. The observatory is south of Traverse City on Birmley Road.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

01/05/2018 – Ephemeris – Telescope Clinic tonight (Has been canceled due to weather)

January 5, 2018 1 comment

Ephemeris for Friday, January 5th. The Sun will rise at 8:19. It’ll be up for 8 hours and 56 minutes, setting at 5:16. The Moon, 3 days before last quarter, will rise at 9:56 this evening.

If you’ve received a telescope for Christmas and are having trouble setting it up, or have an unused one in a closet, basement or attic, bring them to Northwestern Michigan College’s Rogers Observatory tonight at 8 p.m. The Grand Traverse Astronomical Society will be holding their annual telescope clinic to help you understand and use your telescope. The clinic will extend through the period that will be set aside for a star party if it’s clear, to test the telescopes and show the owners how to use them. Like anything telescopes take some time to learn how to use them and find celestial objects. It took me 15 minutes to find Saturn with a telescope the first time I tried, and I knew where it was in the sky. The observatory is south of Traverse City on Birmley Road.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Link to my December 26 post on telescope basics to start you off:  https://bobmoler.wordpress.com/2017/12/26/

Can’t make it tonight? Members are generally available at star parties at the observatory when time permits to help folks who bring their telescopes out. See http://www.gtastro.org for our current schedule of events for 2018.

Updated 7:02 p.m.

12/26/2017 – Ephemeris – Help for that Christmas telescope

December 26, 2017 1 comment

Ephemeris for Tuesday, December 26th. The Sun will rise at 8:18. It’ll be up for 8 hours and 49 minutes, setting at 5:08. The Moon, at first quarter today, will set at 1:34 tomorrow morning.

Get a telescope for Christmas? Or is there one lurking in a closet or attic? Tonight’s a good time to get it out, if it’s clear, because there’s a first quarter Moon out. I consider the Moon round the first quarter to provide the finest viewing.  To get started, most astronomical telescopes have a small finder scope attached. Daytime is the best time to align them on a distant object. To find anything, even the Moon, use the lowest power eyepiece. In most scopes that’s a 20 to 25 millimeter eyepiece. Eyepieces with lower numbers are higher power. Most amateur astronomers use their lowest magnification 90% of the time. The bright planets right now are in the morning sky, and only Jupiter is worth looking at. It’s easy to find because it’s the brightest star-like object, and in the southeast before 7:30 a.m. To help you further, on January 5th, at Northwestern Michigan College’s Rogers Observatory the Grand Traverse Astronomical Society will host its annual Telescope Clinic for telescopes new and old.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Here’s a handout we make available at these telescope clinics:

Telescope Basics

Telescope Types

                           Telescope Types

There are two basic telescope types: The refractor or refracting telescope and reflector or reflecting telescope. The reflecting type shown is a Newtonian telescope, is the simplest and most inexpensive reflector. The Catadioptric (Mirror-Lens) telescope uses a corrector plate in front of the telescope. The one shown is a type called a Maksutov-Cassegrain. The more popular type is the Schmidt-Cassegrain which uses a thin, nearly flat corrector plate. The Cassegrain design uses a convex secondary mirror the sends the light back through a hole in the Primary mirror (O) to an eyepiece.

Refracting telescopes get expensive in a hurry as the diameter of the objective (O) lens increases due to the requirements of at least 4 lens surfaces of the at least two lenses that make it up. The reason for it is to correct for color fringes that would result around bright objects seen through it (chromatic aberration), and the optical quality of the glass required. Reflectors primary mirror have a single surface and the glass simply supports it. The corrector plates of the catadioptric telescopes don’t create chromatic aberration because they don’t bend light much. Telescopes are rated by the diameter of their objectives (O). One could purchase an 11 inch Newtonian telescope for less than $1,000, An 11” Schmidt-Cassegrain for $2,500, or an 11” refractor for the cost of a Lexus.

The reason astronomers go for wider telescopes (greater aperture) is two-fold: To gather more light to better see faint objects, and to increase resolving power, the ability of the telescope to see fine detail and be able to use higher magnification. We’ll see the rules when we talk about eyepieces.

Telescope Mounts

Telescope MountsThere are four basic mounts. Equatorial mounts have to be aligned to the earth’s axis in order to work properly to follow objects in the sky. Alt-Azimuth mounts are the simplest and easiest to set up, but all but the most sophisticated cannot be made to track objects in the sky as the Earth rotates. A relatively new addition to mounts is the computerized “Go To” feature allows the telescope to find objects itself when the mount is properly aligned to the sky. Telescopes with Dobsonian mounts have the largest aperture for the buck. Cheap telescopes tend to have cheap mounts that are hard to use and wobbly, especially the ones with German equatorial mounts. An alt-azimuth mount would be steadier and a whole lot easier to use in this case.

Finder Telescopes

The telescope eyepiece covers so little area of the sky to make finding anything virtually impossible. So all telescopes have small finder scopes attached of 6 to 10 power, or 1 power devices that put a finder circle or red dot on the sky when you look through them. A newer finder idea is a mount for a green laser that projects a beam in the atmosphere toward the object to be located. The author prefers a finder with an aperture of at least 50mm to be able to see most of the dim objects he’s looking for. In the main telescope, use the lowest power eyepiece because it has the widest field of view.

Eyepieces

Magnifying power or magnification is not a telescope property. The eyepiece is essentially a magnifying glass to view the real image that the objective lens or mirror produces at the focal plane (F) in the telescope type diagram on the first page. The focal length of the objective lens or mirror or the effective focal length of the mirrors of the catadioptric telescope divided by the focal length of the eyepiece gives the magnification of that particular combination of telescope and eyepiece. The focal length of the eyepiece is marked on the eyepiece. The telescope focal length may or may not be stamped or marked on the telescope, if not, check the owner’s manual for that quantity.

A telescope will generally come with one or two eyepieces, The lowest power eyepiece will generally be a 25mm eyepiece of some kind. Eyepieces come in 2 standard barrel sizes, 1 ¼ inch and 2 inch. There are some old telescopes that only accept sub 1 inch eyepieces. You may have to hunt to see if any of those size eyepieces are still around. The cheaper the telescope the crummier the eyepiece. Decent eyepieces start at around $35 and go up from there. The best way to tell which eyepiece fits your needs is to ask an astronomer what eyepiece he or she is using at a star party.

About magnification. The highest usable magnification in a telescope is calculated as the aperture in millimeters times 2.4 or aperture in inches times 60. After that the image becomes fuzzy and dim. It’s due to the wave nature of light. I halve those values in his experience. I’d rather have small crisp images than big fuzzy ones devoid of contrast.

A handy accessory to have is a Barlow lens, a negative lens in a tube, that the eyepiece is slipped in before inserting the pair in the eyepiece holder. It will double the power of the eyepiece. So with two eyepieces and a Barlow four separate magnifications are available. The author would rather us a lower power eyepiece with a Barlow than a high power eyepiece of the same power. In that same vein a good low power wide-angle eyepiece is generally the first extra eyepiece astronomers purchase. More expensive ones can be like viewing the universe in IMAX. Here is a truism: Amateur astronomers use their telescope’s lowest power 90% of the time.

Solar filters that fit over the front of the telescope and finder is a fine addition to any telescope and allow viewing of our star close up. Some old telescopes have a solar filter that fits in an eyepiece. For your visual health take the filter and beat it to death with a hammer, and throw it away. There are also filters that can filter out some of the light pollution for dim nebulae. There are filters also to bring out detail in planets.

Above all, have fun! If you have any questions ask that friendly amateur astronomer over there, standing by his or her telescope at the next star party.

03/17/2017 – Ephemeris – When Ireland had the largest telescope in the world

March 17, 2017 Comments off

Ephemeris for St. Patrick’s Day, Friday, March 17th.  The Sun will rise at 7:50.  It’ll be up for 12 hours even, setting at 7:51.  The Moon, 3 days before last quarter, will rise at 1:01 tomorrow morning.

In the 19th century Ireland laid claim to having the largest telescope in the world.  It was a reflecting telescope with a mirror diameter of 72 inches.  It was built by William Parsons the Third Earl of Rosse.  The base of the telescope tube rested in a pit between two massive walls and could only look in a north-south direction.  It saw first usage in 1847.  The telescope was called the Leviathan of Parsonstown, and was in use until 1890.  Mirrors in those days was made of a silvery alloy called speculum.  Two mirrors were used alternately because speculum tarnished.  The mirror not in use would have to be re-polished and swapped in from time to time.  It was the largest telescope until the 100 inch at Mt. Wilson was put in service in 1917.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Leviathan of Parsonstown

The 72 inch Leviathan of Parsonstown. source: http://www.klima-luft.de/steinicke/ngcic/persons/rosse3.htm

M51 drawing

A drawing of the Whirlpool Galaxy, M51 (NGC 5194 & 5195) by Lord Rosse with the 72 inch telescope. Public Domain.

M51 photo

The Whirlpool Galaxy, M51. Credit Scott Anttila.

The Whirlpool Galaxy is the only galaxy that I’ve actually visually seen spiral arms on.  It was seen using a Celestron 14″ telescope at Northwestern Michigan’s Joseph H. Rogers Observatory.  That was a looong time ago.