Attribution: Statis Kalyvas – VT-2004 programme
© Justin Starr 2015
On the night of Wednesday, February 11th, I took my new telescope out onto the balcony to get a glimpse of the setting Venus. I had been eager to see her phases with my own eyes for some time. Yes, Venus has phases just like our own natural satellite, the Moon! This is because Venus (and Mercury, for that matter) are inferior planets, meaning they are between us and our star. Sometimes we are looking at Venus when she is near the opposite side of the Sun (Naturally, we cannot see a full Venus because the Sun would be in the way). This placement lights up most of her face. As she swings around, moving closer to being between us the Sun, we begin to see more and more of her back; she increasingly wanes into a crescent while also becoming significantly larger in apparent angular size as well. Consider this: due to the Moon’s eliptical orbit, its distance from the Earth ranges from 225,804 miles (363,396 km) to 251,968 miles (405,504 km). This results in a measly 14% difference in angular diameter from perigee to apogee – a difference that can’t even really be discerned by the unaided eye. Venus, however, is orbiting the Sun, not us. Therefore, her distance from us can range from 24 million miles (38 million km) to 162 million miles (261 million kilometers)! While the range of 9.5 arcseonds – 61 arcseconds will also not be easily noticed by the naked eye, check out the above image for the drastic difference noticed through a telescope!
15-02-11 Sh*tty Venus capture… but it’s definitely not a perfect circle!
Back to that fateful night: I peered through the eyepiece and saw a squished circle. For the first time in my life, I was able to see Venus as more than just a remarkably bright point of light in the early morning or evening sky that was without any type of definite shape. Here she was, in all her glory, with a limb sheared off by shadow. However, the seeing was rather poor that night. The turbulent atmosphere due to weather conditions was compounded by her low placement in the sky. This location brought her closer to the rooftops of the heat sink in which I reside, also known as New York City. The warmth radiating off of these buildings made her very jittery – violent air currents stretched and squeezed her, making her writhe and pulsate. I wanted to know what her actual phase was and how it compared to view I was being provided in these terrible observing conditions. I took to Twitter and asked of anyone who would listen:
Does anyone know of a site/resource that tells you Venus’s current phase?
— Justin Starr (@UrbanAstroNYC) February 12, 2015
Below are some of the useful responses I received. I encourage you to make use of them the next time you go and observe Venus.
@UrbanAstroNYC http://t.co/CKQaYgjiSi :-)
— Michael Hyde (@mickhyde) February 12, 2015
@UrbanAstroNYC The USNO has an web app for that. http://t.co/QEVQNc9n7z — Joseph Gruber (@JosephGruber) February 12, 2015
@UrbanAstroNYC http://t.co/qgESiae2Bi — Nuno Fragoso Gomes (@nfragle) February 12, 2015
The three tweets shown above were my favorites because they included nice visual renderings that were aesthetically pleasing as well as useful. Some of the results below are still quite useful but are more data/word oriented than visual.
@UrbanAstroNYC Its in the @BritAstro Handbook too. Check overseas pricing (probably about 25 of your US 60p notes) at http://t.co/xAYRTM5dLd
— David Clapham (@DClaphamFRAS) February 13, 2015
@UrbanAstroNYC I see you have had loads of replies but I’ll add my 2 cents in…. http://t.co/PidVdPfAhM — P A R K E R (@JP_Astronomy) February 13, 2015
@UrbanAstroNYC @nfragle google works for me! http://t.co/uvZMDId9qR
— Summer (@Summer_Ash) February 12, 2015
@niais@Summer_Ash@UrbanAstroNYC jpl ephemeris?
— Josh Peek (@jegpeek) February 12, 2015
If any of you readers has other suggestions for resources that you use, please feel free to tweet them to me or leave a reply in the comment section. Clear skies!
