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Crescent Venus and Mercury Observing

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#1 Alnitak2009

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Posted 23 May 2020 - 09:42 AM

Hi all,

 

Got to see these two planets recently. Venus is a large thin crescent and Mercury is small and at gibbous phase. My friend has a C11 in a roll off observatory but with the planets being so low they were behind the wall. Eventually they were lower in the sky  and we were able to view them through an open entry door way:) With much of the telescopes aperture cut off but they did allow us to take a quick peek.

 

He has a deck on the west side of the entryway to the observatory.

 

I was thinking of a decent grab and go scope with modest magnification on a tripod to best be able to view planets when they  are low on the horizon. I was thinking of something like a  small Mak or spotting scope on a tripod with zoom.

 

Don


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#2 Tony Flanders

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Posted 23 May 2020 - 10:13 AM

Yes, it is an extraordinary view. You only get to see Venus this thin and high once in its 8-year cycle, and having Mercury in the same field of view is a huge bonus. They were just a bit more than 1 degree apart on Thursday and Friday evenings.

 

My view to the west is heavily obstructed, so I viewed the pair on Thursday about an hour before sunset, while they were still high. Venus is readily visible all day long if you know where to look, and Mercury is findable in a scope once you have found Venus -- assuming that the sky conditions are good.

 

Venus is blatantly crescent in 10x binoculars.


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#3 Alnitak2009

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Posted 23 May 2020 - 10:30 AM

Yes, it is an extraordinary view. You only get to see Venus this thin and high once in its 8-year cycle, and having Mercury in the same field of view is a huge bonus. They were just a bit more than 1 degree apart on Thursday and Friday evenings.

 

My view to the west is heavily obstructed, so I viewed the pair on Thursday about an hour before sunset, while they were still high. Venus is readily visible all day long if you know where to look, and Mercury is findable in a scope once you have found Venus -- assuming that the sky conditions are good.

 

Venus is blatantly crescent in 10x binoculars.

Hi Tony,

 

I've seen it with the naked eye a few times while the sun was low in the sky. I have a hard time for my eyes to focus at infinity when there are blue skies. If the moon is nearby or a cloud I can focus. There were times that I knew the area where it might be but could not see it , then with luck my eyes focused and there it was easy after finding.

 

Don


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#4 Bortle9

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Posted 23 May 2020 - 10:36 AM

Last night I was able to enjoy a brief first light with my new Zhumell Z130 of Venus and Mercury. Sliver-crescent Venus looked wonderful, especially with the 10mm, if not a little "boily" being so low on the horizon and in a Dob which was not acclimated (although collimation seemed excellent to my untrained eye). Was able to see both at the same time, at extreme sides of the view, in the 25mm! In the 10mm Mercury looked like a tiny disc, but I couldn't discern its phase.

 

My Celestron Apex 102 is very good for grab and go with modest magnification. Recently enjoyed great views of Jupiter and Saturn with it. My low quality zoom spotting scope, SVBONY SV28, is next to useless for skygazing. Perhaps better results can be had with something of higher quality, but I've yet to hear of a great zoom spotting scope or binoculars.

 

Interesting story of viewing thru the doorway!


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#5 CollinofAlabama

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Posted 23 May 2020 - 07:28 PM

I had my SkyWatcher 72ED on original Vixen Portamount out on Thursday and caught both easily.  I had my wife and daughters come look at them, and both fit, easily, even in the Nagler 13mm T6, which has a 2.4˚ TFOV with that eyepiece at 32.3 power, with Venus' large crescent easily discernible, and even Mercury's gibbous-to-half-full globe visible, too.  Was too involved with family matters last night to get a peak, and we just had another incredible hail storm, with cloudy skies forecast until at least Tuesday the 26th.  According to Stellarium, although technically still in the western skies, Venus will be REALLY low on the 26th a good 25 minutes after sundown.

 

I live in one of the flattest places on earth, the Caprock, or Llano Estacado, a huge, flat plain, leveled at the end of the last Great Ice Age, and the largest, most amazingly flat land a person's likely to see, especially at 744 to 1214 meters above sea level, in a very mild grade from south (lower) to north (higher).  The end of the movie Castaway was filmed in the Caprock town of Canadian, with Tom Hanks going to deliver the lost package to the artist-woman divorced from her philandering Muscovite husband to give you an idea of this "Sea of grass" as Coronado christened it on Colonial Spaniards' first viewing in the 1540's.  Point being, I can get a very clear view of the western horizon (any horizon, actually), but she'll be low on the 26th, and I'm not inclined to view any celestial body that close to the sun in broad daylight, running the risk of frying my optic nerve.  No thanks.  If I can't catch her on the 26th, I'll have to wait until November and December 2021, when Venus will be a beautiful crescent again in the western skies.  If the Fates allow, I'll make it.


Edited by CollinofAlabama, 23 May 2020 - 07:36 PM.

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#6 Alnitak2009

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Posted 24 May 2020 - 09:40 AM

Here is a quick snapshot of Venus the other night  with my 40x optical zoom point and shot camera on a tripod. 40x really captures the crescent easily. Have to set the timer to keep the shot steady.

 

Don

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  • Venus.jpg

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#7 REC

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Posted 24 May 2020 - 01:21 PM

Yes, it is an extraordinary view. You only get to see Venus this thin and high once in its 8-year cycle, and having Mercury in the same field of view is a huge bonus. They were just a bit more than 1 degree apart on Thursday and Friday evenings.

 

My view to the west is heavily obstructed, so I viewed the pair on Thursday about an hour before sunset, while they were still high. Venus is readily visible all day long if you know where to look, and Mercury is findable in a scope once you have found Venus -- assuming that the sky conditions are good.

 

Venus is blatantly crescent in 10x binoculars.

I wasn't aware that Venus is so thin and only every 8 years. I go out and glance at the the western sky to see both of them with the naked eye and can't believe how much NW is has gone from a couple of months! I am recovering from a hip surgury and can't take my scope out to see Venus. Maybe I can find a way to just get the ST-80 table top to view the crescent shape?



#8 JoeInMN

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Posted 24 May 2020 - 06:17 PM

I wasn't aware that Venus is so thin and only every 8 years. I go out and glance at the the western sky to see both of them with the naked eye and can't believe how much NW is has gone from a couple of months! I am recovering from a hip surgury and can't take my scope out to see Venus. Maybe I can find a way to just get the ST-80 table top to view the crescent shape?

 

 

We see the crescent phases more often than every eight years (It will be a similar waning crescent in December of next year for instance), but it's not always positioned as high as it's been this time around. The angle of the ecliptic in the spring, and Venus also happening to be positioned a bit above it, just make this evening apparition particularly favorable. To see how much it matters, here are Stellarium screenshots of two sunset skies, one from late April of this year, and the other as it will look in mid-September of 2026. Venus is in a similar thinning crescent phase at both times, but in the first shot its altitude is a good 37°, whereas in the second it is barely more than 8° above the horizon. The slanted orange line is the Ecliptic.

 

stellarium_venus_evening_altitudes.jpg

 

We can of course also see Venus as a waxing crescent in just a few weeks, when it comes around into the morning sky.


Edited by JoeInMN, 24 May 2020 - 06:23 PM.

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#9 Jon Isaacs

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Posted 24 May 2020 - 08:06 PM

Venus has been spectacular.  I love following it as it as an evening "star", it's just a wonderful way to begin an evening under the night sky. At first it changes very slowly but I start to get excited once it's 50% illuminated.

 

Right Now, I'm in pigs heaven. My wife and I have been watching it in an 80 mm ED/apo.. I love the thin crescent along with the atmospheric dispersion.. 

 

Sometimes I get so excited I get dressed in my fancy duds just to view Venus..

5350389-Jon with the NP-101 in his bike clothes.jpg
 
If anyone is viewing Venus with a fast achromat like Tony's 80 mm GoScope, I recommend leaving the large lens cover in place and only removing the small cover in the center. This dramatically reduces the chromatic aberration, it can look very app like even at high magnifications..
 
Jon

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#10 Jon Isaacs

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Posted 24 May 2020 - 08:35 PM

Yes, it is an extraordinary view. You only get to see Venus this thin and high once in its 8-year cycle, and having Mercury in the same field of view is a huge bonus. They were just a bit more than 1 degree apart on Thursday and Friday evenings.

 

 

:waytogo:

 

I noticed that Venus was a thinner crescent than I had remembered but I didn't know why.

 

Thanks

 

Jon


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#11 CollinofAlabama

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Posted 25 May 2020 - 02:59 AM

You look ready to ride, Jon!  Unfortunately our forecasts have gotten worse, and now partly cloudy skies on Wednesday are my next best shot!  Oh well, enjoy her while you can, folks, and thanks for the photo, Don.  She’s a beauty!


Edited by CollinofAlabama, 25 May 2020 - 03:14 AM.

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#12 Tony Flanders

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Posted 25 May 2020 - 05:41 AM

I wasn't aware that Venus is so thin and only every 8 years.


Venus is a thin crescent twice during each of its 19-month synodic cycles -- just before it comes between us and the Sun (in the evening) and just after (in the morning). That adds up to a total of ten times per 8 years.

 

The 8-year cycle is due to the fact the 13 Venus-years (13*224.65 ~= 2920 days) is almost exactly equal to 8 Earth-years (8*365.26 ~= 2922 days). So every 8 years, Venus, Earth, and the Sun are lined up almost exactly the same in space.

 

However, few people view Venus in the morning, especially at this time of year! That cuts the opportunities roughly in half. And of the five possible evening apparitions, Venus is fairly low in the sky during three of them. So you can only see the thin phase when Venus is hugging the horizon.

 

For observers at mid-northern latitudes, this is by far the best of Venus's evening apparitions. Venus was hanging very high right up to one month before inferior conjuction. That gave an unusual opportunity to view Venus as a cresent in a fully dark sky. At this point it is plunging down toward the Sun, but even now, just a week before inferior conjunction on June 3rd, it remains above the horizon almost to the end of nautical twilight.

 

Conversely, this is the worst of Venus's evening apparitions for viewers in the southern hemisphere. It's all a matter of how the ecliptic is inclined with respect to the horizon.

 

That's a summary of the very first article that I wrote as a Sky & Telescope editor, published 16 years and one month ago. Ah, how time flies!


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#13 Loren Gibson

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Posted 25 May 2020 - 07:58 AM

I was a bit confused by reading that Venus is this thin and high once every 8 years, but I get it after clarification.

 

I observed Venus in July of last year [edit: upon further review, more likely c. 10/28/18; I neglected to record the date in my file foreheadslap.gif ] when its elongation was only 7 degrees, which presents a very fine crescent, finer than what we've seen the past few days. It was a broad daylight observation, done in the early afternoon. Daylight observing when it's that close to the sun is a bit difficult to do, but if you have a way of pointing the telescope reliably on the target, and always safely avoiding pointing in the direction of the sun, it can be done. You need a nice clear sky with little or no haze-inducing aerosols. (As a consequence of the time of observation it was very high in the sky, too. grin.gif )

 

Loren


Edited by Loren Gibson, 25 May 2020 - 08:19 AM.

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#14 mkothe

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Posted 25 May 2020 - 10:28 AM

.

Venus is blatantly crescent in 10x binoculars.


I was surprised how obvious and pretty the crescent was in my 15x50is binoculars. I would not have attempted Venus in binoculars if it weren’t for Mercury nearby.

#15 CollinofAlabama

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Posted 25 May 2020 - 05:50 PM

The crescent has been amazingly obvious right now.  Thanks, Tony Flanders for your excellent contribution to this thread, Cloudy Nights, and astronomy in general.  Your post and Minnesota Joe's graphics go a long way explaining why this particular Venusian eastern elongation is so nice!  And I'm glad, Tony, you pointed out that most folks will miss the morning ones.  Although I have done morning astronomy before, with kids these days, that seems completely unrealistic for me, as, no doubt, for many others.  Nothing wrong with being a morning person, but I, like most astronomers, am a night owl.  It's remotely possible that some point in the future, once the kids are older and I'm retired, I might stay up all night for a western elongation, and then, vampire-like, crash exhausted as the sun brightens the sky, but I'd just as soon wait the 16 months later for the evening one.  An all-nighter gets less and less appealing as the years pile up.  It gets pretty hard for me to stay awake after 4 AM these days.  Getting old.

 

Also, not only is Venus' crescent so easy to spot, in my aperture-starved SkyWatcher 72mm ED I could easily make out the half-full-to-gibbous phase of Mercury at 32.3 power.  Oh well, this has been an excellent Venus eastern elongation season.  One to remember, for sure.  Even if these last few days get wiped out by cloudy skies, last Thursday, and the many days before, have just been fantastic!  What hallowed beauty the Goddess of Love hath bestowed upon the sons of men.  And my wife and daughters liked her, too (à la Groucho Marx)



#16 charlesgeiger

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Posted 25 May 2020 - 06:52 PM

Nothing but clouds and/or rain in the PNW.  I was hoping to see this event.  Maybe there will be a break tonight but it was raining earlier with some sun breaks now.  I will get out my 10X42's.

Charlie



#17 dustyc

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Posted 25 May 2020 - 07:38 PM

Going out again tonight. The deep cresent looks really beautiful. Easily matches the inferior conjunction a few years ago as Venus was about 6 degrees (?) away from the sun at about noon against a vivid blue sky. Love the huge size too!!


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#18 Tony Flanders

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Posted 26 May 2020 - 06:12 AM

When Venus is in its waning thin crescent phase, there is a perfectly safe way to view it in the late afternoon. That is the most convenient time to do so even right now, and it will soon become the only possible time. At the time of writing (May 26th), Venus will be 13.5 degrees from the Sun at sunset -- give or take a half degree, depending on your precise location -- and decreasing by 1.5 degrees per day. Once Venus comes within 5 or 6 degrees of the Sun, it's so low after sunset that it's hard to get a decent view. But it can be viewed in the afternoon just a day or two before inferior conjunction with the following method.

 

Find a building that blocks the Sun in the late afternoon. Think about the Sun's trajectory, and make sure the Sun won't re-emerge around the side of the building, or in a kink in the roofline. Then set up your scope at the precise edge of the shadow, so that the Sun is just barely hidden. You can see the Sun's location as a bright spot along the roofline, and if you know the direction and distance from the Sun to Venus (findable with any planetarium program or app), it should be easy to locate Venus with your telescope, binoculars, and conceivably even your unaided eyes.

 

The crescent gets truly startling when it's less than 1% lit, just a faint whitish fingernail clipping against the blue sky.


Edited by Tony Flanders, 26 May 2020 - 06:13 AM.

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#19 DHEB

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Posted 26 May 2020 - 06:29 AM

I have just spent 40 minutes outside under the Sun (at noon here). The plan was to observe Venus and Mercury during daytime with my 102 mm f/4.5 refractor. I started at the Sun (with a filter), moved a bit eastwards, took away the filter, and after a short move promptly arrived to Venus. Beautiful thin, delicate crescent, "properly" colored in the fast achromat. Now, towards Mercury, which I have not observed in several years. I thought it should not be that difficult, as it was at the moment nearly 9° to the east and 2° down from Venus. I can navigate counting telescopic fields, as I do with variable stars at night. But nope. I hoped from Venus, counting fields, and zigzagging in the ballpark area without finding it. Several times, with slightly different "strides". Will try again while Mercury is reasonably far from the Sun. Hopefully the clear weather lasts. Wish me luck.


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#20 Alnitak2009

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Posted 26 May 2020 - 06:08 PM

I have just spent 40 minutes outside under the Sun (at noon here). The plan was to observe Venus and Mercury during daytime with my 102 mm f/4.5 refractor. I started at the Sun (with a filter), moved a bit eastwards, took away the filter, and after a short move promptly arrived to Venus. Beautiful thin, delicate crescent, "properly" colored in the fast achromat. Now, towards Mercury, which I have not observed in several years. I thought it should not be that difficult, as it was at the moment nearly 9° to the east and 2° down from Venus. I can navigate counting telescopic fields, as I do with variable stars at night. But nope. I hoped from Venus, counting fields, and zigzagging in the ballpark area without finding it. Several times, with slightly different "strides". Will try again while Mercury is reasonably far from the Sun. Hopefully the clear weather lasts. Wish me luck.

Mercury would be difficult during the daytime. It is about 0.0 magnitude. Venus is -4

The other night Venus was low in the sky and then next was Mercury shining brightly (brighter than I can remember) and next was a very thin crescent moon. What a cool sight to behold. Good luck trying to find Mercury during the day.

 

Don


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#21 Tony Flanders

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Posted 26 May 2020 - 08:48 PM

I have just spent 40 minutes outside under the Sun (at noon here). The plan was to observe Venus and Mercury during daytime with my 102 mm f/4.5 refractor.


This is dramatically much easier at 5 pm than at noon. The sky is significantly darker, and in my experience it is vastly easier to see something when it is above the Sun than when it is the same distance to the side of the Sun. Which is in turn much easier than when the object is below the Sun.


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#22 DHEB

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Posted 27 May 2020 - 02:36 AM

This is dramatically much easier at 5 pm than at noon. The sky is significantly darker, and in my experience it is vastly easier to see something when it is above the Sun than when it is the same distance to the side of the Sun. Which is in turn much easier than when the object is below the Sun.

Yes, I have seen Mercury before in those conditions, both above and below the Sun. This time I was out for the challenge.



#23 Loren Gibson

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Posted 27 May 2020 - 09:03 AM

Mercury would be difficult during the daytime. It is about 0.0 magnitude. Venus is -4

The other night Venus was low in the sky and then next was Mercury shining brightly (brighter than I can remember) and next was a very thin crescent moon. What a cool sight to behold. Good luck trying to find Mercury during the day.

 

Don

 

Mercury is indeed difficult during the day, but I've done it several times, including at a small elongation. If you "sweep" for it, you can easily run right over it without noticing it because of its low contrast against the sky.

 

Loren


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#24 KI5CAW

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Posted 28 May 2020 - 10:21 AM

I've been watching the crescent thin by observing in daylight when Venus crosses the meridian. She is easy to find using old school setting circles, and my scopes are blocked by trees to the west.

A few apparitions ago I was able to observe Venus near the time of closest approach to the Sun; a huge thin crescent. I had my mount axes firmly locked to prevent any possibilty of slewing across the Sun itself, and a long shield attached to the telescope. That year I was able to see Venus in broad daylight.


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#25 spereira

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Posted 31 May 2020 - 10:07 AM

Moving to Solar System Observing, for a better fit.

 

smp




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