APOD: Venus Transits the Midnight Sun (2012 Jun 20)

[Anthony Barreiro]

... In the State of Victoria in the south eastern part of Australia, the indigenous folk recognise six seasons ( no so called "autumn" or "fall" perhaps because indigenous vegetation here is non-deciduous. There's more here: http://home.vicnet.net.au/~herring/seasons.htm

Wow, straight from late summer to early winter. I would miss autumn, the light is so lovely ... .

[astro-newbie]

I'm a bit confused. The desription says,

"The remarkable scene looks north over the Norwegian Sea from Sortland, Norway."

Despite the fact that the sun is at its northernmost point seen in the sky, wouldn't it still be toward the SOUTH as viewed in Norway? Isn't this a picture of the SOUTHERN horizon around midnight?

Thanks.

[Chris Peterson]

I'm a bit confused. The desription says,

"The remarkable scene looks north over the Norwegian Sea from Sortland, Norway."

Despite the fact that the sun is at its northernmost point seen in the sky, wouldn't it still be toward the SOUTH as viewed in Norway? Isn't this a picture of the SOUTHERN horizon around midnight?.

On the summer solstice, above the Arctic Circle, the Sun reaches its highest point in the southern sky at noon. It is above the horizon all day, and at midnight is due north. In Sortland, on June 20, the Sun reached an altitude of about 45° above the southern horizon as it crossed the meridian at noon, and was just above the northern horizon as it crossed the meridian at midnight.

[ddale51]

Boy, am I confused. Apparently the position and direction of travel of Venus as it crosses the sun varies hugely depending on the location of the observer on Earth. This photo shows Venus traveling across the sun's face in a horizontal position from roughly 10 o'clock to 2 o'clock. But from where I watched the transit--about 38 degrees latitude in the US--Venus began its transit at about the 1:00 position and was traveling "downward" toward the 5:00 position. That's about a 90 degree tangent from this photo! I just can't the visualize how these varying perspectives are possible. Is there a diagram somewhere that can explain this to this confused soul?

[Chris Peterson]

Boy, am I confused. Apparently the position and direction of travel of Venus as it crosses the sun varies hugely depending on the location of the observer on Earth. This photo shows Venus traveling across the sun's face in a horizontal position from roughly 10 o'clock to 2 o'clock. But from where I watched the transit--about 38 degrees latitude in the US--Venus began its transit at about the 1:00 position and was traveling "downward" toward the 5:00 position. That's about a 90 degree tangent from this photo! I just can't the visualize how these varying perspectives are possible. Is there a diagram somewhere that can explain this to this confused soul?

Venus traveled from east to west across the northern part of the Sun. The Sun is only tipped about 7° from the ecliptic, and Venus is only inclined a few degrees from it. So it makes sense that in the far north, when the Sun is moving parallel to the horizon, that the ecliptic, and therefore the apparent motion of Venus will be parallel to the horizon as well, with the north pole of the Sun pointing upwards.

The relationship between the direction of Venus's path and the local horizon depends entirely on the latitude of the observer. Like the Moon and other astronomical objects, apparent orientation in the sky varies widely with your location.

Everybody on Earth saw this event just as the chart shows, except they saw the Sun's north pole pointing is some different direction with respect to the horizon.

[ddale51]

Thanks Chris! I understand now. Your explanation was clear and helpful.