Astronomical Sunrise/sunset/longest day of year

[Andrea J.]

Someone Private messaged me thinking i have the answer to this question.
I have no answer other than "maybe it has to do with Aruba being so close to the equator.

here is the question

"I was looking at the sunrise-sunset chart. June 21, 2010 is the longest day of the year for Boston, MASS. I looked on the chart for the longest day in Aruba and believe it or not the chart shows July 11 as the longest day. Why?"


so, my question is "why????" i have no idea. Do any of you?

[ChuckiesDad]

Sunrise and Set

Hours of daylight are longer the further north you travel from the equator during the summer due to the tilt of the Earth's axis. The northern part of the planet is tilted closer to the sun so is exposed to more sunlight. On the equator or closer, in the case of Aruba, there is less tilt, thus less difference between the length of day and night.

For example, on June 21:

Boston has 15 hours 16m 50s of daylight
Anchorage Alaska 19 hours 22m 23s of daylight
Aruba 12 hours 51m 41s of daylight

As to the June vs. July , perhaps I misunderstand the question but

Boston, Massachusetts has 13 minutes more daylight on Jun. 21 vs. Jul. 11

Jun 21, 2010 15 hours 16 minutes 50s of daylight
Jul 11, 2010 15 hours 03 minutes 42s of daylight

[rob o]

Originally Posted by Andrea J.

"I was looking at the sunrise-sunset chart. June 21, 2010 is the longest day of the year for Boston, MASS. I looked on the chart for the longest day in Aruba and believe it or not the chart shows July 11 as the longest day. Why?"

Chuckie's Dad gave a nice synopsis....let me add a little.

The longest day in the northern hemisphere (as measured by the length of time between sunrise and sunset) occurs on or about June 21 (varies a day or so depending on the most recent leap year).

Now here's where there might be some confusion.....the earliest sunrise and the latest sunset do not occur on the same day. For example....earliest sunrise in Boston is typically around June 15.....latest sunset around July 4.

Ever wonder what that "figure eight" on the back of your globe in the middle of the Pacific Ocean was for....that's for finding "high noon" (middle of the day), which rarely occurs at 12:00. For example, in Aruba in April, "high noon" actually occurs around 12:40. At 12:40 on April 23rd in Aruba, sun is directly overhead....a flagpole would have no shadow!

[Andrea J.]

very interesting.

thanks for the answers.

[cukiecutr]

This is interesting. I will be in Bostson on 6/21 and Aruba 7/11. I can't wait to get there.

[rob o]

Originally Posted by cukiecutr

This is interesting. I will be in Bostson on 6/21 and Aruba 7/11. I can't wait to get there.

Best wishes on your upcoming wedding.

You will find it interesting how early the sun sets in Aruba versus Boston that time of year.

[lizzardo]

Here is an interesting site with the sunrise/sunset for
any month/year here. This one is for June 2010

http://www.timeanddate.com/worldcloc...&afl=-11&day=1

We don't have the big 'change' in daytime because we are so
close to the equator - but this is a cool site if you want to look
further into it.

[Sgroi135]

Awesome!!! I will be getting there on the 10th!

[CPhT Nancy]

The July 11 longest day must be a typo. The longest day in Aruba (the summer solstice) is June 21. with 12h 51m 41s of sun.

[lizzardo]

Here is a really cool site that shows the projected time of daylight

http://www.gaisma.com/en/location/oranjestad-aw.html

Lots of cool graphs and stuff

Not much difference