Search found 4 matches

by bill ritchie
Mon Jul 04, 2022 9:46 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Strawberry Supermoon Over Devil's Saddle (2022 Jul 04)
Replies: 9
Views: 1936

Re: APOD: Strawberry Supermoon Over Devil's Saddle (2022 Jul 04)

A lovely sequence. It is also a good example of refraction. The 'tangents' to the six images are in a noticeable curve, caused by the decreasing refractive 'uplift' as the elevation above the horizon increases.
by bill ritchie
Mon Nov 01, 2021 10:07 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Aphelion Sunrise (2017 Jul 05)
Replies: 9
Views: 4076

Re: APOD: Aphelion Sunrise (2017 Jul 05)

"So the most distant sunrise occurs during northern summer, when the planet's north pole is tilted toward the Sun and the north enjoys longer, warmer days." Conversely, the Sun is closest in the Southern Hemisphere Summer. That is why New Zealand, Australian, South African and South Americ...
by bill ritchie
Wed Oct 06, 2021 9:35 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: Sunrise at the South Pole (2021 Oct 05)
Replies: 23
Views: 16468

Re: APOD: Sunrise at the South Pole (2021 Oct 05)

Is not the "length of sunrise" the time between the appearances of the upper and lower limbs? At the 2021 Southward equinox, the Sun's apparent diameter was 31.8'. The Sun's declination (= the earth's tilt) was 0° 15.9' N at about 02:59 UTC on 22nd Sept, and 0° 15.9' S at about 11:41 UTC o...
by bill ritchie
Sun Aug 08, 2021 10:04 pm
Forum: The Bridge: Discuss an Astronomy Picture of the Day
Topic: APOD: A Perseid Below (2021 Aug 08)
Replies: 12
Views: 2793

Re: APOD: A Perseid Below (2021 Aug 08)

Fascinating photo. Around 60 degrees North at around a local time of 2300, looking North West, gives the correct Sun / star / Perseus aspects for 13th August 2011 (or any other year!). That doesn't help much with longitude. But whilst orienting the stars, I noticed the double red object about 4.5 me...