{"id":27742,"date":"2022-01-04T13:27:03","date_gmt":"2022-01-04T13:27:03","guid":{"rendered":"https:\/\/www.skyatnightmagazine.com\/?p=103152"},"modified":"2022-01-04T13:41:10","modified_gmt":"2022-01-04T13:41:10","slug":"how-to-observe-and-photograph-a-crescent-venus","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/how-to-observe-and-photograph-a-crescent-venus\/","title":{"rendered":"How to observe and photograph a crescent Venus"},"content":{"rendered":"

<\/p>

By Pete Lawrence\n \t\t<\/p>

Published: Tuesday, 04 January 2022 at 12:00 am<\/p>

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Venus is the brightest of the planets, regularly appearing brighter than mag. \u20134.\u00a0It also has the largest potential apparent size, something which is only achieved close to inferior conjunction.<\/p>\n

A good challenge is to see whether you can spot the planet\u2019s phase with your eyes only.<\/p>\n

When Venus<\/a> is close to inferior conjunction<\/a>, it appears through the eyepiece<\/a> as an ultra-thin crescent.\u00a0It also approaches the theoretical limit of naked-eye resolution, at 1 arcminute.<\/p>\n

It will appear larger than 1 arcminute between 1-17 January 2022<\/strong> and it\u2019s not uncommon to \u2018see\u2019 the phase of Venus when staring at it.<\/p>\n

\""Photograph\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
As a thin crescent, Venus is an incredible sight through a telescope. Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n

Unfortunately, this often turns out to be down to visual errors in your eye\u2019s optical path rather than a true phase. Don\u2019t worry, Venus is tricky in this respect!<\/p>\n

A common issue when viewing a bright point source of light is the presence of astigmatic rays that emanate from the point, which can produce the appearance of a crescent shape.<\/span><\/p>\n

If you see a clear <\/span>shape to the planet, tilt your head. If the shape appears to rotate, it is in your head.<\/p>\n

Observing crescent Venus<\/strong><\/h2>\n

Part of the challenge of observing the crescent Venus in January 2022 will be to locate Venus itself (for more on this, see our guide to observing the planets in January 2022<\/a>).<\/p>\n

As Venus is close to the Sun, make sure you observe safely, and <\/span>only when the Sun is below the horizon.<\/p>\n

Consider enlisting help from someone who <\/span>(a) you know has good eyesight, and (b) knows little about astronomy or Venus.<\/p>\n

Don\u2019t prompt them with any information, just ask them to look hard at the planet and write down what they see.<\/p>\n

If they can see a shape to the planet, ask them to draw its orientation relative to the horizon.<\/p>\n

\""An\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
An image showing the phases of Venus, captured by Roger Hutchinson, London, UK, 25 March 2017. This image won the Planets, Comets & Asteroids category of the 2017 Astronomy Photographer of the Year competition.<\/span><\/figcaption><\/div>\n

Another thing to try is to use a large sheet of card with a hole, placed some distance from you.<\/p>\n

Looking at Venus through the hole without the distraction of its surroundings may help.<\/p>\n

Remember, if you see something, does its orientation stay the same if you tilt your head?<\/p>\n

This is a scientific experiment and as such you may report a negative result, which is fine. If you experience a positive result, we\u2019d love to hear from you, along with the date, time and details of any method used.<\/p>\n

You can email us at contactus@skyatnightmagazine.com<\/a> and let us know how you got on.<\/p>\n

Crescent Venus phases and dates<\/strong><\/h2>\n
<\/colgroup>
Date<\/th>Phase (%)<\/th>Diameter (arcseconds)<\/th><\/tr><\/thead>
1 January 2022<\/td>0.025<\/td>60.9<\/td> <\/tr>
2 January 2022<\/td>0.020<\/td>61.4<\/td> <\/tr>
3 January 2022<\/td>0.015<\/td>61.8<\/td> <\/tr>
4 January 2022<\/td>0.011<\/td>62.1<\/td> <\/tr>
5 January 2022<\/td>0.008<\/td>62.4<\/td> <\/tr>
6 January 2022<\/td>0.006<\/td>62.6<\/td> <\/tr>
7 January 2022<\/td>0.004<\/td>62.7<\/td> <\/tr>
8 January 2022<\/td>0.003<\/td>62.8<\/td> <\/tr>
9 January 2022<\/td>0.003<\/td>62.7<\/td> <\/tr>
10 January 2022<\/td>0.004<\/td>62.7<\/td> <\/tr>
11 January 2022<\/td>0.005<\/td>62.5<\/td> <\/tr>
12 January 2022<\/td>0.008<\/td>62.3<\/td> <\/tr>
13 January 2022<\/td>0.010<\/td>62.0<\/td> <\/tr>
14 January 2022<\/td>0.014<\/td>61.7<\/td> <\/tr>
15 January 2022<\/td>0.018<\/td>61.3<\/td> <\/tr>
16 January 2022<\/td>0.023<\/td>60.8<\/td> <\/tr>
17 January 2022<\/td>0.028<\/td>60.3<\/td> <\/tr>
18 January 2022<\/td>0.034<\/td>59.7<\/td> <\/tr>
19 January 2022<\/td>0.041<\/td>59.1<\/td> <\/tr>
20 January 2022<\/td>0.048<\/td>58.5<\/td> <\/tr>
21 January 2022<\/td>0.055<\/td>57.8<\/td> <\/tr>
22 January 2022<\/td>0.063<\/td>57.1<\/td> <\/tr><\/tbody><\/table><\/div>

Photographing crescent Venus<\/strong><\/h2>\n

A telescopic view of Venus in January will show its beautiful crescent phase and the planet\u2019s brilliance makes it ideal for imaging.<\/p>\n

The low altitude, however, will play havoc with the finesse of the crescent, wobbling the sharp cusps and rendering them blurry.<\/p>\n

This can be offset by imaging during the day. Although the altitude of the planet never gets high, a little higher does make a difference. Also, the effects of temperature gradients are less severe in the day.<\/p>\n

\""Phases\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Credit: Pete Lawrence<\/span><\/figcaption><\/div>\n

A high frame rate camera fitted to a telescope will give the best results, and as you\u2019re going to be imaging through blue sky during the day, it\u2019s recommended to fit an infrared pass filter to the camera\u2019s front.<\/p>\n

This has two benefits: firstly, it will darken the surrounding blue sky to black and second, it will reduce the effects of atmospheric turbulence.<\/p>\n

Locating Venus in daylight carries a danger with it due to the proximity of the Sun. If your mount has setting circles<\/a>, these are a great help.<\/p>\n

If you\u2019re not sure what you\u2019re doing, attempt to image when Venus is either in the morning sky before sunrise, or in the evening after sunset.<\/p>\n

Whichever method you use, it\u2019s well worth capturing the Venusian crescent.<\/p>\n

Recommended equipment<\/strong><\/h3>\n