147 replies to this topic

[Overtime]

A few nights last week I saw something I was sure wasn't a planet when I looked up in front of my house ( unaided, just my eyes ). As usual I was in sort of a rush so grabbed my Celestron 4.5 x 900mm scope since its's easier to move. I first used a 40mm, all I saw was a bright dot. I swapped in a 20mm and it was still a dot. I added a 2x barlow and it was a slightly bigger dot. I added a 5x barlow lens and it was still a dot. Is Venus to small to easily view or was something else hindering my view? I even star tested the collimation and it looked good ( a few days before I had replaced the focuser ). My guess was Venus was so much smaller then Jupiter and Saturn it was harder to see?

[Neanderthal]

Venus is covered in gas and reflects a lot of light. Without a filter, it's pretty much just a bright spot. With a filter, it's pretty much a bright little ball, with some mottled hues of yellow/green. It's hard to see much.

Edited by Neanderthal, 11 December 2024 - 01:37 PM.

[Overtime]

Venus is covered in gas and reflects a lot of light. Without a filter, it's pretty much just a bright spot. With a filter, it's pretty much a bright little ball, with some mottled hues of yellow/green. It's hard to see much.

LOL, that explains why I didn't see what I expected.

[bobzeq25]

A few nights last week I saw something I was sure wasn't a planet when I looked up in front of my house ( unaided, just my eyes ). As usual I was in sort of a rush so grabbed my Celestron 4.5 x 900mm scope since its's easier to move. I first used a 40mm, all I saw was a bright dot. I swapped in a 20mm and it was still a dot. I added a 2x barlow and it was a slightly bigger dot. I added a 5x barlow lens and it was still a dot. Is Venus to small to easily view or was something else hindering my view? I even star tested the collimation and it looked good ( a few days before I had replaced the focuser ). My guess was Venus was so much smaller then Jupiter and Saturn it was harder to see?

Note that the distance to Venus is MUCH more variable than the distance to Jupiter and Saturn. Catch it when it's (apparently) closer the the Sun, and it _may_ be much larger. And it will not be round, it has phases like the Moon. Part of the evidence that convinced people the Earth was not at the center of the Solar System, way back when.

Edited by bobzeq25, 11 December 2024 - 02:01 PM.

[plunk111]

Venus shouldn't be a ball right now - should look like a half moon, even in a small telescope. Maybe you were looking at a star?

[Tony Flanders]

Venus shouldn't be a ball right now - should look like a half moon, even in a small telescope. Maybe you were looking at a star?

Venus is actually 64% lit right now, and probably looks even fuller than that through the eyepiece. Nonetheless it should be very obvious even at a low 45X magnification that it's an extended -- though completely featureless -- object, and definitely truncated on one side.

 

If not, as suggested above, you were likely looking at a star. One diagnostic is that under reasonably dark skies Venus appears almost painfully bright through a telescope.

[mikeDnight]

I love observing Venus!  It is both beautiful and challenging. The challenge lies in detecting the subtle cloud top detail, which is almost at the limit of detectability, but once seen becomes obvious though never easy. Another challenge lies in following the planet throughout its phase change, which can become dangerous if done without care, as the very thin crescent phase is only seen when the planet's line of sight lies very close to the Sun. You'll only make a mistake once, so it's best to observe with the Sun hidden behind a wall or roofline. Venus gets very large and also can take magnification well. Colour filters can aid in detecting the subtle detail, but rather than straining to see the shaded areas, first try to pick out the brighter regions, then everything else starts to reveal itself. It's true that not everyone is able to see detail as it leans toward the UV, but don't give up too easily. It's easy to imagine you aren't seeing anything when in reality you may just be expecting darker shades to jump out. Any sketch of Venus, as in those below, are out of necessity an exaggeration in intensity. 

 

 

 

Below FS128

 

 

Below FC100DZ 

 

Edited by mikeDnight, 11 December 2024 - 02:21 PM.

[Neanderthal]

@Mike,

Nice penmanship! 

 

@ Overtime,

I rarely look at Venus when near or at full stage. Experiment with filters for best results.

[ShaulaB]

It might be time to get an app like Stellarium or Sky Safari (my preference). Apps and software make identifying "What is it?" a breeze. Even a resource like Skymaps dot com help differentiate between stars and planets. https://www.skymaps.com/downloads.html

 

As has been stated, Venus goes through phases like the Moon does. It's gibbous, or potato shaped, right now. When planets are low on the horizon, lower than 30 degrees altitude, it's harder to get detail. Venus' great brightness overwhelms a lot of small optical systems like what you were using.

 

Venus is the third brightest natural sky object, after the Sun and the Moon. Venus is brighter than any star.

[Dave Mitsky]

Venus is on its way to inferior conjunction on March 22nd when it will be more or less between the Earth and the Sun.  Near the time of inferior conjunction Venus will appear as a thin crescent that's much larger in apparent size than Jupiter is at its closest opposition.
 

https://in-the-sky.o...20250323_11_100
 

Venus can vary in angular diameter from a minimum of 9.7 arc seconds to a maximum of 66.1 arc seconds.  Jupiter varies from 29.8 arc seconds to 50.1 arc seconds.
 

It will be at a maximum eastern angular elongation of 47.2 degrees from the Sun on January 10th.
 

https://earthsky.org...t elongation is
 

https://in-the-sky.o...20250110_11_101
 

Venus will be at dichotomy (i.e., illuminated 50%) on January 11th.

https://in-the-sky.o...20250112_11_100

[Dave Mitsky]

Here's a graphic from Wikipedia that displays the phases of Venus.

Images of Venus taken during the elongation east of 2020 can be seen at https://www.coelum.c....jpg&w=900&zc=1

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[Sketcher]

Is Venus a difficult view?

 

It can be.  But it can also be a remarkably easy and remarkably beautiful view.  Much depends on all the details of the specific observing situation -- the telescope, the sky conditions, the planet's phase, whether one's making a daytime observation, a bright twilight observation, a deep twilight observation, a dark sky observation, etc.  Then there's Venus's altitude in one's sky and one's seeing conditions.  Color filters can "spice up" one's views under darker sky conditions and even aid in the visibility of subtle cloud details.

 

Furthermore, observer experience can be a very big deal with Venus.  Some "experienced" observers have said there's nothing to see with Venus other than the phases.  Others have been able to see and sketch subtle shadings in the Venusian clouds -- details that have sometimes been verified via some of the better images that have been taken of the planet.

 

Try studying the planet under different sky darkness levels -- a dark sky, deep twilight, light twilight, and even daytime.  Try using color filters, particularly green, some deep blues, purple, and violet.  Use as much magnification as seeing conditions and the telescope permit.

 

But a telescope of poor optical quality and/or observer inexperience can indeed convince a person that Venus isn't worth bothering with.

 

As others have basically mentioned, when Venus is near its full phase, it can appear relatively small.  When it's a thin crescent, it will appear to be significantly larger than any of the other planets can ever appear to be.  Unfortunately, Venus will be very near the Sun in one's sky when it's a very thin crescent and one will most likely need to make a daytime observation while being very careful to not permit any sunlight from entering one's telescope.  The subtle cloud shadings will likely be easier to see when Venus near its quarter phases.

 

I used the thick rail on a roll-off-roof observatory to block the Sun when making the below observation with a rather small 80mm refractor:

 

 

But don't even try that until you're very familiar with the Sun's apparent motions in one's sky and the shortness of the time period you'll have to safely make the observation.  This is an area where both, experience and knowledge can be essential in protecting your vision.

 

Unfortunately, I've not photographed and uploaded any of my Venus observations that made use of color filters and show cloud shadings, But I've made such observations using telescopes from 80mm up through 12-inch apertures.

 

Bottom line:  Venus can be every bit as beautiful as its very fitting name!

[Starman1]

Venus is visible in the west right now and is definitely the brightest object in that part of the sky, and visible earlier in twilight than anything else except the Moon.

It only takes 50-75x to see that Venus is not full.  For now over the next few weeks, Venus will grow larger and brighter, and more crescent-shaped.

It will gradually grow closer to the sun and disappear, only to reappear in the morning sky before sunrise.

It will then be a crescent and gradually get smaller, less bright, and less full over the following weeks.

Edited by Starman1, 11 December 2024 - 06:34 PM.

[Dave Mitsky]

Another factor comes into play when observing Venus when it is low in the sky, namely atmospheric prismatic dispersion, also known simply as atmospheric dispersion.  

 

https://www.astropix...dispersion.html

https://cseligman.co...cdispersion.htm

 

https://britastro.or...em-and-solution

Here's a hand-held afocal iPhone photo that I took of a crescent Venus that demonstrates the effect.

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[ButterFly]

A few nights last week I saw something I was sure wasn't a planet when I looked up in front of my house ( unaided, just my eyes ). As usual I was in sort of a rush so grabbed my Celestron 4.5 x 900mm scope since its's easier to move. I first used a 40mm, all I saw was a bright dot. I swapped in a 20mm and it was still a dot. I added a 2x barlow and it was a slightly bigger dot. I added a 5x barlow lens and it was still a dot. Is Venus to small to easily view or was something else hindering my view? I even star tested the collimation and it looked good ( a few days before I had replaced the focuser ). My guess was Venus was so much smaller then Jupiter and Saturn it was harder to see?

Venus is the brightest thing in the western sky at sunset.  It's hard to miss.  If your scope was pointed at the brightest thing in the western sky, based on this report, your telescope wasn't anywhere near focus.  Move your telescope to a bright star, focus, then move back to Venus.  Of course, you could have not been pointed at Venus at all, like others suggest.  It's so much brighter than anything else around it, that that is really unlikely.  You would have noticed that brightness difference.

 

Venus is about 19" across right now, and Jupiter is about 48" across, so about 2.5x bigger looking.  With your 20mm eyepiece in your 900mm focal length scope, you get about 45x.  That would make Venus appear about fourteen arcminutes across.  That's doable to see Venus' half moon shape - except for all that glare at night.  This would be something to try while it's still twilight.  With your 2x barlow, that makes Venus about 28 arcminutes across in your eyepiece.  That's about the size of the full moon naked eye.  That's very easy see as a half moon shape - again, without glare getting in the way.  Try that again during twilight as well, and compare its size in the eyepiece to the moon naked eye.  At 5x barlowed,  we're talking  about two and a quarter full moons naked eye.  Venus' glare is bad, but not that bad.  You were nowhere near focus!

 

To help put this in context for you, Galileo was the first person to have recorded seeing Venus' phases through a telescope.  The magnification Galileo used to make those observations was at most around 30x.

 

Your telescope is much better than anything Galileo ever had.  Just get it in focus.

[Alex65]

I usually observe Venus while it is still twilight. This means that the disc isn't too bright, and I can see it so much better, than when it is dark and the planet is so bright that I can't really make out anything. Plus, it will be higher up during twilight (I have even observed Venus during the day) than when it gets dark and the planet is close to setting. 

[Overtime]

Venus shouldn't be a ball right now - should look like a half moon, even in a small telescope. Maybe you were looking at a star?

It was just before sunset and stellarium gave me the idea it was Venus. My apps have steered e wrong before. Next time Ill get a phone only picture.

[Overtime]

Another factor comes into play when observing Venus when it is low in the sky, namely atmospheric prismatic dispersion, also known simply as atmospheric dispersion.  

 

https://www.astropix...dispersion.html

https://cseligman.co...cdispersion.htm

 

https://britastro.or...em-and-solution

Here's a hand-held afocal iPhone photo that I took of a crescent Venus that demonstrates the effect.

It was just before dusk so it probably was bad seeing/viewing.

[mikeDnight]

Dave Mitsky & Alex65 mention a very important point. Don't observe Venus against a black background sky! As long as the Sun is shielded from direct view of the scope you can even observe Venus in full daylight providing you can find it. If you know where it is, you'll see it with the naked eye no problem in full daylight.

[RMay]

As long as the Sun is shielded from direct view of the scope you can even observe Venus in full daylight providing you can find it. If you know where it is, you'll see it with the naked eye no problem in full daylight.

Venus can be seen in daylight, but the seeing needs to be fairly clear/transparent, as haze can block a naked eye view.

 

I happened upon it a couple of days ago as a naked eye object while fiddling with my Questar Seven. Below is an untracked handheld iPhone grab showing it at maybe 55% full.

 

The other image is from inferior conjunction taken on Aug 12 last year with my 3.5, when it was just a few degrees away from the sun (which was shielded by my front porch overhang).

 

Venus is indeed an interesting daytime target…

 

Ron

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[N-1]

I took some photos of Venus through my 8" Dob last month, and the phase is still similar now but with the planet appearing somewhat larger. We rarely have great seeing here, but it was good enough to yield some informative images:

 

Visual band:

 

...and in grayscale:

note the cloud shadings

 

Violet-Filtered (Wratten #47)

 

Note the cloud shadings. Both of the above allowed for albedo markings to be observed visually, especially with the violet filter. Unfiltered, it was a very subtle affair.

 

Near Infrared (850nm longpass):

 

And UV (Baader U):

 

The seeing would have to be non-existent for Venus to not yield at least some aspect through a telescope that sets it apart from the other planets.

Edited by N-1, 12 December 2024 - 08:47 PM.

[Sebastian_Sajaroff]

I guess that you observed an object other than Venus.

As of now, Venus is 19" (as big as Saturn’s globe) and it’s 64% lit. Even at 50x you should see a small gibbous disk.

Most of the time, Venus shows nothing other than its phase and its heavenly white colour, most details are usually captured in UV and IR. However, from time to time, those markings shift to violet and become vaguely visible to our eyes (I saw them myself 3 times in the last 4-5 years, make sure you have excellent seeing conditions)

Edited by Sebastian_Sajaroff, 13 December 2024 - 07:15 AM.

[mikeDnight]

Venus can be seen in daylight, but the seeing needs to be fairly clear/transparent, as haze can block a naked eye view.

 

I happened upon it a couple of days ago as a naked eye object while fiddling with my Questar Seven. Below is an untracked handheld iPhone grab showing it at maybe 55% full.

 

The other image is from inferior conjunction taken on Aug 12 last year with my 3.5, when it was just a few degrees away from the sun (which was shielded by my front porch overhang).

 

Venus is indeed an interesting daytime target…

 

Ron

  I love your image of Venus close to inferior conjunction Ron. Zooming in on the crescent, it definitely appears that the illumination from behind has extended the crescent phase way beyond the north & south poles. This is something I've seen visually on a number of occasions, making the globe stand out against the slightly brighter sky background. 

 

 

Edited by mikeDnight, 13 December 2024 - 04:17 PM.

[RMay]

I love your image of Venus close to inferior conjunction Ron. Zooming in on the crescent, it definitely appears that the illumination from behind has extended the crescent phase way beyond the north & south poles. This is something I've seen visually on a number of occasions, making the globe stand out against the slightly brighter sky background.

Mike, thank you for your kind words; they are greatly appreciated!

Your (and really all sketches posted in this thread) are quite lovely, and provide a great record of the event. Well done!

Ron

[Sketcher]

A note on the unilluminated portion of Venus appearing to be darker than the sky around it:  This would have to be an illusion of some kind.  It's impossible for anything beyond Earth's atmosphere to actually be seen as being darker than the sky around it.  The light from Earth's daytime illuminated sky would be glowing in front of any object that's more distant.

 

One might think that a total solar eclipse is an exception, but it's not.  During a total solar eclipse, the new moon can appear to be darker than the Sun's corona around it because the corona does not exist in front of the moon.  It's behind the moon.  When on Earth looking at Venus, Earth's illuminated daytime sky is not behind Venus.  It's in front of Venus.