2015 Sky Calendar
Seasons and the Sun
Saturday, January 3rd, 8:36pm HST
At this time, on this day, the Earth is 147,098,291 km or 91,402,640 miles from the Sun. This position is known as perihelion and it is the closest the Earth gets to our star.
Friday, March 20th, 12:45pm HST
The Vernal or Spring Equinox is this day. In the Northern Hemisphere this is celebrated at the first day of spring. This is often thought of as one of two days when there is 12 hours of day and 12 hours of night; in fact, the name ‘equinox’ comes from the Latin words aequus (equal) and nox (night). Despite the name, this is incorrect. An equinox is actually a day that the Sun is directly over the Equator at solar noon; the Sun’s highest point in the sky. Because timezones do not follow the Earth’s lines of longitude exactly, and the same time zone is used for a number of lines of longitude, solar noon is usually not the same a local noon.
NOTE: In Hilo, March 14th will be the day with the closest amount of equal day and night. On this day, daylight will last for 12 hours and 7 seconds.
Monday, May 18th, 12:17pm HST
The first of two occurrences of Lahaina Noon takes place on this day. Lahaina Noon is the local Hawaiian term for the tropical phenomena that sees the sun pass directly overhead at solar noon—and as a result, vertical objects, like lamp posts, will cast no shadows. As described above, because of the imperfections and limitations in the human-drawn time zones, this doesn’t occur exactly at local noon, but at 12:17pm. The exact date and time of Lahaina Noon changes depending on your latitude in the tropics. The date and time listed here are for Hilo. Lahaina Noon is a modern name for this event. Ancient Hawaiians called it kau ka lā i ka lolo—“the sun rests on our brains.”
Sunday, June 21st, 6:38am HST
The Summer Solstice occurs on this day. This is the first day of summer in the Northern Hemisphere. This is the date and time that the sun is directly over the Tropic of Cancer, the most northerly point it reaches. For places north of the equator, like Hawai’i, this is the longest day of the year. North of the Tropic of Cancer, this is also the day which the sun reaches its highest point in the sky. In the tropics, however, this occurs during the two instances of Lahaina Noon.
Monday, July 6th, 9:40am HST
At this time, on this day, the Earth is 152,098,233 km or 94,509,460 miles from the Sun. This position is known as aphelion and it’s farthest the Earth gets from the Sun.
Friday, July 24th, 12:27pm HST
The second instance of Lahaina Noon in Hilo. Again, you can see that because of the imperfect time zones, this occurs at 12:27pm instead of 12:00pm.(see above for more information)
Tuesday, September 22nd, 10:20pm HST
The Autumnal or Fall Equinox is this day. In the Northern Hemisphere this is marked at the first day of fall. As with the Spring equinox, day and night are not actually equal on this day. See the ‘Spring Equinox’ entry for more information. NOTE: In Hilo, September 29th will be the day with the closest amount of equal day and night near the fall equinox. On this day, daylight will last for 11 hours, 59 minutes and 34 seconds.
Monday, December 21st, 6:48pm HST
The Winter Solstice occurs on this day. This is the first day of winter in the Northern Hemisphere. This is the date and time that the sun is directly over the Tropic of Capricorn, the most southerly point it reaches. For places north of the equator, like Hawai’i, this is the shortest day of the year and the day which the sun’s elevation at solar noon is it’s lowest.
NOTE 1: HST is the abbreviation of Hawaii Standard Time. HST is 10 hours behind CoordinatedUniversal Time (UTC). This is often shortened to “UTC -10:00”.
NOTE 2: Hawaii does not observe Daylight Saving Time.
Phases of the Moon – 2015
|New Moon||First Quarter||Full Moon||Last Quarter|
|January 4||January 12|
|January 20||January 26||February 3||February 11|
|February 18||February 25||March 5||March 13|
|March 19||March 26||April 4||April 11|
|April 18||April 25||May 3||May 11|
|May 17||May 25||June 2||June 9|
|June 15||June 24||July 1||July 8|
|July 15||July 23||July 31||August 6|
|August 14||August 22||August 29||September 4|
|September 12||September 20||September 27||October 4|
|October 12||October 20||October 27||November 3|
|November 11||November 18||November 25||December 2|
|December 11||December 18||December 25|
Special Lunar Events
The Full Moon on March 5th is a Micro Moon
A Micro Moon is a moon that reaches the full phase when it is farthest from Earth—a position known as apogee. Although micro moons do not appear smaller than other full moons (the difference is only a few percent), it does have a noticeable effect on Earth. Because the moon is farther from Earth, the gravitational pull of the moon on Earth decreases: causing tides on the Earth’s oceans that are smaller and lower than normal. This is true whenever the moon is at apogee, regardless of whether or not it is full.
Total Lunar Eclipse on April 3rd/4th
Here in Hawai’i will be one the best places on Earth to view this total lunar eclipse. A lunar eclipse is when the Moon passes through the shadow—called the umbra—of the Earth turning the moon red. This colour is why lunar eclipses are often called ‘Blood Moons’. For a blood moon or total lunar eclipse to occur the sun, earth and moon must be perfectly aligned. This does not happen too often as the moon does not orbit the earth in the same plane as the earth orbits the sun.
The eclipse will begin when the moon starts to enter the earth’s penumbra or partial shadow at 11:01pm on April 3rd. The moon will begin entering the umbra—and start turning red—at 12:16am on April 4th. This will last until 3:45am when it exits the umbra. The moon will clear the penumbra at 4:59am (all times in HST).
The Full Moon on July 31st is a Blue Moon.
A Blue Moon is not a moon that is literally blue, but refers to the second full moon in a single calendar month. As the lunar cycle lasts about 29.5 days, this is a fairly rare occurrence: we see a blue moon about once every two to three years.
Interestingly this is not the original definition of a blue moon. Originally, a blue moon was the third full moon in a season with four full moons. As the year has four seasons of about three months each, there is usually three full moons in a season. When there was an extra, a fourth full moon, the third moon was called a blue moon. The modern definition using calendar months is from a misinterpretation of an article in a 1946 issue of Sky & Telescope magazine1.
The Full Moon on September 27th is a Super Moon.
A Super Moon is the opposite of a micro moon. It is a full moon that occurs when the moon is at perigee; the closest it gets to Earth. Again, like a micro moon, there is no noticeable difference in the size of a super moon and a regular full moon. Because the moon is closer to Earth, however, there are noticeable differences in the tides. Tides are bigger and higher when the moon is at perigee than when it is not.
Some people claim that super moons cause natural disasters because of the stronger gravitational pull exerted on the Earth. While it is true that the gravitational pull is slightly larger, this is why the Earth experiences big tides, it has very little, if any, effect on the internal dynamics of the planet. The Earth’s own gravity is far stronger than that of the moon and it has no trouble withstanding the gravitational pull of the moon irregardless of how close or far the moon is from Earth. Additionally, if the super moon was causing, say, large increases in tectonic activity, we would see a large decrease in such activity during micro moons, when the moon is at apogee. No evidence for this exists.
A lunar eclipse will also take place during this full moon creating a “Super Blood Moon”. Unfortunately, it will not be very visible here in Hawai’i: the eclipse starts before the moon rises. In Hawai’i, the moon will rise above the eastern horizon at 6:13pm. By 6:27pm the moon will have exited the umbra, ending the ‘blood moon’ phase of the eclipse. It will exit the penumbra at 7:22pm. If the horizon is clear though, you could see a large, red moon rising in the east opposite the setting sun.
1 “What is a Blue Moon?” - TimeAndDate.com
Major Meteor Showers in 2013
|Name||Peak Date||Zenith Hourly Rate*|
|Eta Aquariids||May 5||30|
*The Zenith Hourly Rate is the maximum rate per hour at the peak of the shower. While the meteor showers peak on specific dates, meteors are often visible for a few days prior to and after the peak date.
The Days of the Week
The origins of our days of the week come from the five planets visible to the unaided eye together with the Sun and the Moon. Monday or Moon Day, Sunday or Sun Day, Saturday or Saturn Day are very apparent and are Old English adaptations of the Roman names. Tuesday was named in honor of Mars (Tiw’s Day was an Old English adaptation of the Norse god of war). Wednesday was in honor of Mercury (Woden’s Day from the Germanic god of wisdom). Thursday was in honor of Jupiter (Thor’s Day to the Norse god of thunder associated with Jupiter). Friday was in Honor of Venus (Frige’s Day from Germanic god of beauty and love associated with Venus).