Venus is the third brightest natural object in the sky and it can be seen in broad daylight with the naked eye.
I have been observing this planet in broad daylight since 1979. It was shown to me by K Rajagopalan who was, I think, one of the founder members Association of Bangalore Amateur Astronomers. My first look-up-and-there-she-is sight of Venus was on the 16th of Feb 1980 during the totality phase of the solar eclipse. But that was no fun – it was visible easily. We just glanced up and it was there.
The fun is in observing this planet is when the Sun is well above the horizon. Finding the planet in the broad daylight is a challenge. If you have a reasonably good clear sky then the challenge is all it’s worth. It will be a thrilling experience. You may also use a telescope or a pair of binoculars.
Trap: if you are myopic or you cannot see a distant object clearly and your ophthalmologist has suggested glasses then you must use those else you will not be able to make out Venus.
Here are some methods you may adopt to locate Venus when the Sun is still above the horizon.
Method 1: Using Moon as a pointer
As the Moon goes around the earth it passes close to every planet once a month. If you know the day when it is closest to Venus and the separation or angle between the two then you can find Venus taking the reference to the Moon, which is not so difficult. And then with its reference, you can find Venus. Here a pair of binoculars helps a lot. The catch is some dates are quite favourable but some are not.
I have tabulated the date and time (in IST), the separation between the Moon and Venus, the declination of Venus and the percentage illumination of the Moon in table 1 below.
Trap: During this apparition of Venus when it is south of the Sun, the declination of the Moon changes from 0° in February to 25° by May. So when they are close to the meridian it would be quite a pain in the neck to use your binoculars. One of the bad days was on 2015 May 21. The separation between the two was nearly 7°.
On 2023 Feb 22 at 3:10 p.m. the Moon and Venus will be separated by 1° 50′ 37″. Venus will be north of the Moon. So first find the Moon and look for Venus to its north. To start with a 7X50 binox will help a lot. It has a field of view of 7°. Venus will be slightly less than 4 lunar diameters north of the Moon.
On 2023 March 24, Venus will be occulted by the Moon. See this link
Table 1
Minimum angular distance between Venus and Moon
Declination
Date Separation Venus Moon Moon ill.
---------------- ----------- -------- ------ -----
2022 Dec 24 17:32 3° 27' 26" -23° 25' -27° 49' 2.0%
2023 Jan 23 15:57 3° 13' 03" -14° 32' -18° 33' 3.5%
2023 Feb 22 15:10 1° 50' 37" +00° 08' -02° 07' 6.0%
2023 Mar 24 16:03 0° 06' 03" +15° 00' +14° 23' 8.9%
2023 Apr 23 18:00 1° 17' 16" +24° 36' +25° 54' 12.4%
2023 May 23 12:36 2° 11' 42" +25° 07' +27° 34' 13.2%
----------------- ---------- -------- -------- ------
Method 2: Catching Venus at the culmination
An imaginary line that passes through the north and south poles of the celestial sphere that also passes through the zenith (the point right overhead) is called a meridian or more specifically observer’s meridian. When a celestial body is on the meridian then it is at its culmination point. It is also said to transit the meridian or simply transits.
Knowing the transit time and coordinates (RA and Dec.) of the Sun and Venus makes it easy to identify Venus. You can get this information from various desktop planetarium software, like Stellarium. You will need to use eclipse goggles as you will be looking at the Sun
How to use this information? Close to the transit time of the Sun stand behind a vertical pillar. Mark the position of your feet. Wearing your Sun goggles, note the position of the Sun on the pillar at the time of transit. Now about 5 to 10 minutes before the transit time of Venus stand where you have marked the position of your feet. Look at the pillar and make mental adjustments for differences in declination. That is if Venus is north or south of the Sun. If, say, the Dec of Venus is 5 deg north of the Sun then you will have to look 5 deg above the point where you make the mark the position of the Sun.
Table 2
For 2023 Feb 22
Geocentric coordinates
RA Dec. Transit
Sun 22h 21.5m -10° 14' 12h 52m
Venus 0h 10.8m +0° 8' 14h 41m
Moon 0h 13.3m -1° 58' 14h 44m
Transits after the Sun
Venus 1h 49m
Moon 1h 52m
Dec difference Sun and Venus Venus 10° 22' north of Sun
Moon and Venus Venus 2° 06' north of Moon
The maps below are drawn for 19.9° latitude
Method 3: Using altitude and azimuth
Again using desktop planetarium software you can generate altitude and azimuth values for the day and time of observations. Generate these values every 10 to 15 minutes as shown below.
Trap: remember this data is very observer’s location and time specific. Separate values should be computed for every location and time.
This table is for Nehru Planetarium, Mumbai
Ephemeris of Venus
Date Time Altitude Azimuth
16 Feb 2023 15:00:00 +67° 26′ 31″ 194° 20′ 10″
16 Feb 2023 15:15:00 +66° 17′ 50″ 203° 25′ 02″
16 Feb 2023 15:30:00 +64° 39′ 48″ 211° 32′ 24″
16 Feb 2023 15:45:00 +62° 37′ 39″ 218° 37′ 21″
16 Feb 2023 16:00:00 +60° 16′ 21″ 224° 42′ 56″
16 Feb 2023 16:15:00 +57° 40′ 07″ 229° 56′ 07″
16 Feb 2023 16:30:00 +54° 52′ 16″ 234° 24′ 58″
16 Feb 2023 16:45:00 +51° 55′ 22″ 238° 17′ 06″
16 Feb 2023 17:00:00 +48° 51′ 25″ 241° 39′ 09″
16 Feb 2023 17:15:00 +45° 41′ 52″ 244° 36′ 38″
16 Feb 2023 17:30:00 +42° 27′ 53″ 247° 14′ 03″
This table told us that at 5:15 p.m. on 16 Feb altitude of Venus was nearly 45° which is halfway between the zenith and horizon and azimuth of 244° means it is nearly halfway between west and southwest. On that evening I stood facing halfway between west and southwest and looked up by 45°. It took me some time but Venus was there. Sunset was at 6:39 p.m.
Method 4: DIY Smart Phone Finder Scope
In early September 2013, we made a Smart Phone Finder Scope. It was published on Instructables. If you are a handyman and you have not visited this site then you must.
The idea is very simple – load a Sky Map app on a smartphone and mount the phone on your telescope. And there you are. As you move the telescope you can see the sky map changing. In fact, you can even use the search option and that will guide you in the right direction. And of course, you can use it at the night too.
The link to the Smart Phone Finder Scope is https://www.instructables.com/Smart-Phone-Finderscope/.
Trap: We have noted that often gyro in the phone pointing is not that accurate – so first get the object in your optical finder scope and then get it to the main scope.
Tip: In the case of misalignment you can put a cross mark or a circle on the screen of your smartphone. Suppose you have got the Moon in the main telescope but on the phone, it is not in the exact centre then just put a mark where the Moon is shown on the screen of the smartphone.
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First sighting of Venus – A dangerous game (to be attempted only by the experts).
Close to its conjunction (superiors or inferior), we lose sight of Venus in the glare of sunlight. At this time it is very dangerous to look for Venus as by mistake you might look at the Sun.
After its superior conjunction, Venus can be seen moving away from the Sun. The idea is to point a telescope towards the Sun. You must cover its primary mirror or the lens with an appropriate solar filter. And ‘lock’ the telescope. After some time the Sun will drift out of the field. After the Sun has completely drifted out, remove the filter. Venus will soon drift into the field of your eyepiece. You may have to correct for the Dec.
Warning: do not attempt this before the inferior conjunction – there is every chance of the Sun drifting into the field of view.
DIYA 