{"id":27048,"date":"2021-12-16T00:00:00","date_gmt":"2021-12-16T00:00:00","guid":{"rendered":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/?post_type=purple_issue&p=27048"},"modified":"2022-01-11T15:57:15","modified_gmt":"2022-01-11T15:57:15","slug":"the-sky-guide-challenge-4","status":"publish","type":"post","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/2021\/12\/16\/the-sky-guide-challenge-4\/","title":{"rendered":"The sky guide challenge"},"content":{"rendered":"\n

Can you spot the phase of Venus with the naked eye over the month of January?<\/p>\n\n

\"\"
After 8 January, the phase of Venus increases as its apparent diameter shrinks (see table below). This diminishes the opportunity to make out the planet\u2019s shape with the naked eye<\/figcaption><\/figure>\n\n

Venus wasn\u2019t the easiest planet to spot in 2021. Loitering in the evening sky after sunset, its altitude has been low. It is visible in the evening sky before inferior conjunction on 9 January 2022, after which it re-emerges in the morning sky. Venus is the brightest of the planets, regularly appearing brighter than mag. \u20134. It also has the largest potential apparent size, something which is only achieved close to inferior conjunction. The challenge is to see whether you can spot the planet\u2019s phase with your eyes only.<\/span><\/p>\n\n

When Venus is close to inferior conjunction, it appears through the eyepiece as an ultra-thin crescent. It also approaches the theoretical limit of nakedeye resolution, at 1 arcminute; it will appear larger than 1 arcminute between 1-17 January and it\u2019s not uncommon to \u2018see\u2019 the phase of Venus when staring at it. 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\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. If you see a clear shape to the planet, tilt your head. If the shape appears to rotate, it is in your head.<\/p>\n\n

Part of this challenge will be to locate Venus itself. As it is close to the Sun, make sure you observe safely, and only when the Sun is below the horizon. Consider enlisting help from someone who (a) you know has good eyesight, and (b) knows little about astronomy or Venus.<\/span><\/p>\n\n

Don\u2019t prompt them with any information, just ask them to look hard at the planet and write down what they see. If they can see a shape to the planet, ask them to draw its orientation relative to the horizon.<\/p>\n\n

Another thing to try is to use a large sheet of card with a hole, placed some distance from you. Looking at Venus through the hole without the distraction of its surroundings may help. Remember,<\/p>\n\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. Enjoy the challenge!<\/p>\n\n

\"\"
Use this table to check the phase and apparent diameter of Venus over the month if you see something, does its orientation stay the same if you tilt your head?<\/figcaption><\/figure>\n\n

PHOTO: PETE LAWRENCE<\/p>\n","protected":false},"excerpt":{"rendered":"

Can you spot the phase of Venus with the naked eye over the month of January?<\/p>\n","protected":false},"author":24,"featured_media":27046,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ub_ctt_via":"","purple_page_number":"55","purple_custom_meta_purple_page_number":"55","purple_seq_number":"1","purple_custom_meta_purple_seq_number":"1","purple_source_article":"article_55-1.xml","purple_custom_meta_purple_source_article":"article_55-1.xml","purple_source_issue":"January-2022","purple_custom_meta_purple_source_issue":"January-2022","purple_external_id":"January-2022-55-1","purple_custom_meta_purple_external_id":"January-2022-55-1","purple_issue_code":"|0000086548||","purple_custom_meta_purple_issue_code":"|0000086548||","purple_android_product":"com.im.skyatnight.200","purple_custom_meta_purple_android_product":"com.im.skyatnight.200","purple_ios_product":"com.im.skyatnight.200","purple_custom_meta_purple_ios_product":"com.im.skyatnight.200","purple_web_product":"","purple_custom_meta_purple_web_product":"","purple_publication_id":"075fab74-0a21-4201-866a-899d6c41c40c","purple_migrated":"","kt_blocks_editor_width":""},"categories":[22],"tags":[14],"featured_image_src":"https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be.jpg","author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"acf":{"readingTimeMinutes":"3","apple_news_title":""},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be.jpg",2048,719,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be-300x105.jpg",300,105,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be-768x270.jpg",768,270,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be-1024x360.jpg",800,281,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be-1536x539.jpg",1536,539,true],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/77\/2021\/12\/709ab903-3652-465f-9f58-8dd9d8d614be.jpg",2048,719,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"Can you spot the phase of Venus with the naked eye over the month of January?","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/27048"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/users\/24"}],"replies":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/comments?post=27048"}],"version-history":[{"count":3,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/27048\/revisions"}],"predecessor-version":[{"id":27669,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/posts\/27048\/revisions\/27669"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media\/27046"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/media?parent=27048"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/categories?post=27048"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/wp-json\/wp\/v2\/tags?post=27048"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}