Planet Gazing Last Night

[Robert Watcher]

A fun night last night. I finally have recognized Saturn in the skies - first picture with the moon. It was so high in the sky sitting just to the right of the moon. (how I would love to have peeked through a long telescope with this clear view)

Leaving the mall the night before, there was a perfect unobstructed view of the moon with Venus and Jupiter below it. By the time I got to our home, only the moon was visible.

Last night, Venus and Jupiter were a little farther away from the moon and the view from our street has lots of wires, but Anne and I headed out onto the street to take the spectacle in - including easily recognizing Saturn in it’s unique occurrence.

The moon and three planets were visible in the sky about half an hour before it got dark. It was nice having my SkyView app to more easily identify everything. The last pic was the best I could retrieve of the small dot Saturn - but the oblong diagonal angle the the rings are kind of visible- especially compared to the round shapes of the other planets. I tried LOL


https://www.google.ca/amp/s/www.space.com/amp/saturn-moon-conjunction-black-friday-2019.html

https://www.space.com/thanksgiving-...lNanJtbkc5cGRlVlVjZ19ydlo0Q2lsemEtel94YTFSMEM.

 

[Robert Watcher]

 

[Robert Watcher]

 

[Jerome Marot]

how I would love to have peeked through a long telescope with this clear view

You would see Saturn ring and Jupiter bands in a small scope. A large instrument is not necessary for these planets.

 

[Robert Watcher]

For

You would see Saturn ring and Jupiter bands in a small scope. A large instrument is not necessary for these planets.

For sure —- but definitely much longer than the reach of my 600mm camera lens.

 

[Asher Kelman]

I am so impressed! My wife can read thecsky as her Dad was a sailor and also it was taught in school!

Howcis it that the sky in the City is clear enough? Had there been rain?

Congrats!

I have to look up more!

Asher

 

[Robert Watcher]

I am so impressed! My wife can read thecsky as her Dad was a sailor and also it was taught in school!

Howcis it that the sky in the City is clear enough? Had there been rain?

Congrats!

I have to look up more!

Asher

it was a clear night for sure. Although that is pretty common here in San Miguel. The skies are rarely cloudy and not overcast often.

 

[Jerome Marot]

For sure —- but definitely much longer than the reach of my 600mm camera lens.

That is not the way astronomical instruments work. For example, I have a small refractor, this one. In photographic terms, it is a 480mm f/6 lens. One can easily see Saturn rings in that instrument, with a reasonably short focal eyepiece, 9 or 6 mm for example.

 

[Robert Watcher]

That is not the way astronomical instruments work. For example, I have a small refractor, this one. In photographic terms, it is a 480mm f/6 lens. One can easily see Saturn rings in that instrument, with a reasonably short focal eyepiece, 9 or 6 mm for example.

interesting. I know nothing about astronomy and telescopes, quite obviously.

I was just using what I have available to photograph the scene in front of me. Saturn, Venus, and Jupiter are very small dots with no details with the 600mm equiv. lens I used. Glad I captured it though.

 

[Asher Kelman]

That is not the way astronomical instruments work. For example, I have a small refractor, this one. In photographic terms, it is a 480mm f/6 lens. One can easily see Saturn rings in that instrument, with a reasonably short focal eyepiece, 9 or 6 mm for example.

Jerome,

That’s a beautiful instrument. What do you use it for? For bird watching it might be awkward to hold and would the view be inverted or the objective corrects that?

I impulsively checked this out, but it’s out of stock! Does one need a computerized rotating mount?

Asher

 

[Jerome Marot]

I was just using what I have available to photograph the scene in front of me. Saturn, Venus, and Jupiter are very small dots with no details with the 600mm equiv. lens I used.

If you look closely at the last image in this thread, Saturn's ring can be seen. One can also see that there is a double image, which is a common problem at these focal lenghts with cameras using a curtain shutter. The relatively high masses of the shutter let the camera move a tiny bit.

 

[Jerome Marot]

That’s a beautiful instrument. What do you use it for? For bird watching it might be awkward to hold and would the view be inverted or the objective corrects that?

I impulsively checked this out, but it’s out of stock! Does one need a computerized rotating mount?

I mainly use that instrument to look at astronomical objects, like the ones portrayed here. For bird watching, an erect prism can be used to make the image stand upright. A rotating mount makes it so that objects like Saturn will not leave the field of view within minutes and a computerised version is so much more convenient that it is well worth the extra price. Note that only some mount types are adapted to photography.

Not all refractors (i.e. instruments without mirrors) are created equal, though. This particular one is well corrected so that images are quite sharp in the eyepiece. As is usual with astronomical instruments, the image is only sharp at the center, so it makes a poor photographic objective. Photographic objectives add lenses near the image plane to correct the sides of the picture.

An alternative to refractors are reflectors (i.e. instruments with mirrors). They can be considerably cheaper for simple designs. Generally speaking, they are a better choice for larger instruments, from 20cm (8") upwards or so. A Celestron C8, for example, is still quite portable and will show more details on Saturn or Jupiter. It will allow one to image Neptune as a blue-green disc, etc.

 

[Asher Kelman]

Thanks to Robert for bringing us our Astronomical sky lesson and you, Jerome for amazing practical guidance for entering this field of interest and fascination!

​

The price of joining the club is one entry level decent camera lens equivalent!

But why is the refractor a better fit for you, Jérôme?

Asher

 

[Jerome Marot]

But why is the refractor a better fit for you, Jérôme?

It is not better, I have the two instruments... The celestron is a more powerful instrument and easy to set up, but the mount is not suited for photography. The refractor, which I got for considerably less money than what you found it for, is a much smaller package, but setup is much more involved.

As a rule of thumb, astronomical instruments are defined by the physical size of the entry (the front lens, if you wish). The word "aperture" is also used, but does not quite have the same meaning as in photography, so I avoid using that word for the moment. This dimension does not define how "fast" the resulting lens is, telescopes are often relatively slow lenses, f/11 is common (but we can let the camera open for hours to collect more light...). That aperture is directly linked to the limits of diffraction, which in turn defines how much we can enlarge the image.
A large entry is necessary to see small objects, and planets are relatively small. OTOH, a large entry also needs the air to be super calm, turbulence is more of a problem for large scopes. A larger entry makes the telescope heavier and more expensive, obviously.

Refractors cannot be made larger than about 15cm in practice as the glass becomes too heavy to hold by its sides. The mirror of reflectors can be held at the back side. OTOH, reflectors need a front mirror to send the light back or to the side and that mirror also creates diffraction.

At one extreme of the scale, professional telescopes have mirrors several meters in diameter and extra optics to remove air turbulence. At the other extreme, binoculars will allow one to resolve Jupiter to a disk and see its 4 main satellites. This is what Galileo Galilei observed with an instrument the size of binoculars in 1610, making history.

 

[Asher Kelman]

Thanks, Jerome,

Do you have kids or grandkids to fascinate with the Stars, planets and their elusive moons?

We gave very clear skies after rain, but I wonder about the lights from the city

Asher