2018 Astronomy Highlights
Every year Bishop Museum’s J. Watumull Planetarium (Honolulu, Hawai‘i) provides a calendar of astronomical events specifically for Hawaii’s location and time zone.
Most sources that list the times for moon phases, meteor shower peaks, the start of the seasons and other events provide that information in Universal Time (UT), which is ten hours ahead of Hawaiian time.
In addition, there are certain celestial events that are specific to Hawai‘i. These include the date of Makahiki which is determined by the first visible sliver of a moon after the new moon after the rising of the Pleiades at sunset (which occurs on November 17 each year).
This calendar also provides the dates and times for “Lāhaina Noon” for many locations in the islands. Lāhaina Noon is the term for the two days each year when the sun is exactly overhead. This only occurs in the tropics, and the dates vary depending on latitude.
In addition to this yearly overview, Bishop Museum provides star maps for each month of the year for Hawaii’s latitude. This resource is available on the Bishop Museum Planetarium website.
Astronomy Events 2018
This super moon is the brightest of 2018 and the first of two in January. The moon will be a little closer to earth than average for a full moon, and thus will be a little bigger and brighter than the norm.
A moon is officially ‘full’ when the sun, earth and moon are in a straight line, with the earth in between the two other celestial bodies.
Supermoon background: the term ‘supermoon’ is a recent invention and has received a fair amount of media attention in the last few years. The term has come to refer to a full moon that occurs when the moon is near its closest point to earth in its slightly oval path around our planet. Since the moon’s path is oval, or elliptical, it can be as close as 225,600 miles from us or as far as 252,000 miles. When the moon is at the closest point to earth in its monthly path around the earth it is said to be at ‘perigee.’ A supermoon is a just a full moon that occurs in the same day that the moon is at perigee. Since it’s a little closer than usual, the moon appears a little large than a ‘normal’ full moon.
The astrologer who coined the term “supermoon” uses the term in reference to both new moons and full moons that occur near perigee. That said, there has been very little interest is ‘super new moons’ since you cannot see a new moon.
Earth at perihelion
This occurs at 7:35 p.m. January 2 Hawai‘i-Aleutian Standard Time. On this day, the earth is only 91.5 million miles from the sun, compared an average distance of 93 million miles. (At aphelion, in July, earth is 94.5 million miles from the sun).
Like all planets, the earth’s orbit is not a perfect circle but rather an oval. Earth reaches perihelion, its closest approach to the sun, in early January each year. Some people think that the change in the seasons is due to how close we are to the sun. However, what really matters here is the tilt of the earth. Each January, while we are closer to the sun than at any other time of the year, the northern hemisphere is tilted away from the sun, and so we experience winter.
Supermoon; Blue Moon; Total Lunar Eclipse – Blood Moon
Lucky Hawaii! In the early morning hours of this day, before sunrise, a lunar eclipse will be visible. Lunar eclipses can only happen during a full moon. They occur two to four time a year but are only visible from the nighttime side of Earth. The moon takes around 3 hours and 23 minutes to cross the Earth’s dark umbral shadow and can turn the moon to an eerie shade of blood red. For Hawaii, the lunar eclipse will begin at 1:48 a.m., reach totality at 3:30 a.m., ending at 5:11 a.m. the morning of January 31 before sunrise. The following is the timing breakdown for different parts of the eclipse from earthsky.org:
Hawaii-Aleutian Standard Time (January 31, 2018)
Partial umbral eclipse begins: 1:48 a.m. HAST
Total eclipse begins: 2:52 a.m. HAST
Greatest eclipse: 3:30 a.m. HAST
Total eclipse ends: 4:08 a.m. HAST
Partial umbral eclipse ends: 5:11 a.m. HAST
Chinese New Year
Chinese New Year occurs two new moons before the first day of spring, which occurs on March 20 this year.
Start of Daylight Saving Time for most of continental US and Canada. As of this day, the east coast is six hours ahead of the Hawaiian Islands and the west coast is three hours ahead of Hawai‘i. The Hawaiian Islands do not observe Daylight Saving Time.
Spring begins at 6:15 a.m. Hawai‘i-Aleutian Standard Time on March 20 (04:31 on March 20 Universal Time).
The second Blue Moon of the year. Both January and March contain two full moons while February has none.
The Sunday after the first full moon after the first day of spring.
Jupiter at opposition
The planet is brighter than any other time of the year and will be visible all night.
When a planet is in opposition, there is a straight line between the sun, the earth in the middle, and the planet. During opposition, a planet rises at sunset, is high at midnight and sets at dawn. During this time, a pair of binoculars will allow you to see the Galilean Moons – the four largest moons of Jupiter.
Saturn at opposition
As with Jupiter in May, Saturn shines at its brightest as it hits opposition on June 27. There is a straight line between sun, Earth, and Saturn; the ringed planet rises at sunset, is overhead all night, sets at dawn.
Earth at aphelion, furthest point from the sun in the earth’s yearly orbit.
Summer begins on June 21 at 12:07 a.m. Hawai‘i-Aleutian Standard. This is the longest day for the northern hemisphere and the shortest for the southern hemisphere.
Mars at Opposition
As seen in May with Jupiter, and June with Saturn, May will be at opposition.
Autumn begins at 3:45 p.m. on September 22 Hawai‘i-Aleutian Standard Time.
Daylight Saving Time Ends
It ends at 2 a.m. for most of continental US and Canada. As of this day, the east coast is five hours ahead of the Hawaiian Islands and the West Coast is two hours ahead.
To mark the start of the Makahiki season: 1) wait for the star cluster of the Pleiades to rise at sunset, which occurs on November 18, 2) wait for the new moon that follows this sunset rising of the Pleiades, which occurs in 2018 on December 7, and 3) wait for the first visible crescent moon that follows this new moon. This year, this slender crescent should be visible in the west at dusk on December 9, thus marking the start of the Makahiki season.
Winter starts at 12:23 a.m. Hawai‘i-Aleutian Standard Time on December.
For all meteor showers, the viewing will be better after midnight. These repeating annual events are caused as the earth enters into debris left over from a specific comet (or, in the case of the Geminids, an asteroid). As the earth goes around the sun, our planet runs into the same debris at the same time each year. This is why these showers occur at the same time each year. After midnight, the part of the earth that you are on is facing toward the debris that causes the meteor shower. This is why all meteor showers are better after midnight.
Meteor star showers are named for the constellation where the meteors appear to come from. The Lyrid shower in named for Lyra, the harp, for example. (The Quadrantid Shower refers to an old constellation called Quadrans Muralis, which is now part of Bootes). Generally, these constellations are rising in the east during the prime post-midnight viewing time for a shower. That said, don’t just look east – scan the entire sky for shooting stars.
To view shooting star showers, just find a dark location (as little city light as possible) and get comfortable (a lawn chair is a good idea).
Quadrantid Meteor shower
Peak night: January 3-4, 2018
The Quadrantids have a sharp, short peak, lasting only a few hours.
With January 1 being the first, and largest, “Super moon” of the year, the sky is too bright to see this meteor shower in its full strength. If you want to try your luck, the best viewing should be in the predawn hours on January 3 (i.e. really early on January 3, from 12:01 a.m. till dawn) and during the predawn hours January 4 (again from 12:01 a.m. ‘til dawn).
The streaks of the Quadrantids appear to come from the constellation of Bootes the Herdsman, in the northeast. “Quadrant Muralis,” or “Mural Quadrant,” an old name for part of the constellation of Bootes. This was one of the now-lost constellations that were done away with when the International Astronomical Union divided the sky into 88 officially-recognized constellations in 1922.
Lyrid Meteor Shower
Peak: April 21- 22, 2018
The best viewing times for the Lyrids will be from 12:01 am to dawn (5:45 am) early on April 21, and from 12:01 am to dawn early on April 22, Time. The shower is active from April 16 – 25. While not one of the strongest showers, the Lyrids can produce up to twenty meteors per hour. The Lyrids come from the debris of Comet C/1861 G Thatcher.
Eta Aquarid Shower
Peak: May 6-7, 2018
Though the peak is from May 6-7, this meteor shower is active from April 19 to May 26, 2018. The portion of Aquarius where the shoot stars radiate rises above the horizon around 3:45 a.m. This is a light shower, 10 to 30 meteors or so per hour when viewed from the northern half of our planet. One claim to fame: this shower is one of two showers caused by debris from Halley’s Comet, along with the Orionids in October.
Perseid Meteor Show
Peak: August 11-12, 2018
This meteor shower is active from July 13 to August 26, but the most active and fruitful dates of this shower are August 11 and August 12. The best viewing time on both the 11th and 12th is from 12:01 until dawn. The new moon is on August 11 which makes 2018 the is the most ideal year for viewing this meteor shower.
The Perseids are the most famous and bountiful meteor shower with up to 80 meteors per hour and the Perseids often leave long trails. The shower is generated by debris from Comet 109 P Swift Tuttle. This comet takes 130 years to orbit the sun, and passed through the earth’s part of the solar system back in 1992, leaving lots of fresh comet debris that led to particularly good showers.
Orionid Meteor Shower
Peak: October 21-22, 2018
The active period for this shower is September 23 – November 27, tough the peak, producing about 20-25 meteors an hour, will be on October 21 and 22. Unfortunately, October’s full moon is on the 24th this year and will cause complications with visibility.
Like the Eta Aquarids in May, this one is caused by debris from Halley’s Comet. Up to 20-25 meteors per hour.
Leonid Meteor Shower
Peak: November 17-18, 2018
The Leonids have an intense peak every 33 years and were responsible for the greatest meteor shower over Hawai‘i in recent times, the 2001 shower. Prior to that 2001 spectacle, the 1966 shower was one of the greatest on record.
Geminid Meteor Shower
Peak: December 13-14, 2018
Like all meteor showers here, the ideal viewing time is from 12:01 a.m. to dawn.
One of the best showers as the meteors are very bright and intensely colored; we in Hawai‘i often have good weather in December to see it well. This meteor shower is a rarity in that it is caused by debris from an asteroid (3200 Phaethon) rather than by comet debris.
In the tropics the sun passes overhead twice during the year. On these two days, at local noon, the sun will be exactly overhead and an upright object such as a flag pole will have no shadow. This phenomenon only occurs in the tropics; the sun is never overhead in any other part of the planet. The northern reaches of the Hawaiian Islands, such as Midway Island, are north of the tropics and do not experience the overhead sun.
The ‘overhead sun’ date varies depending on how far north or south you are in the tropics. Thus, for Līhu‘e on Kaua‘i, this occurs on July 12, at 12:42 p.m. Further south, on the Island of Hawai‘i, the overhead sun date occurs on July 27 (12:26 p.m. for Hilo, 12:30 p.m. for Kailua Kona).
Here in the islands a term we often use for zenith noon is “Lāhaina Noon.” This is a modern term, selected by Bishop Museum in a 1990 contest held to select a name for the zenith noon phenomenon. The term “Lā haina” means ‘cruel sun’ in Hawaiian, and while the sun in the islands is almost never cruel, it can be pretty intense as it shines directly down from the zenith.
Another phrase that one hears in Hawai‘i for the zenith sun is “kau ka lā i ka lolo,” which translates as “the sun rests on the brains.” This expression is discussed in the book 1972 book Nānā I Ke Kumu (Pukui et. al.) as being a “phrase designating high noon; the time when ‘the sun is directly overhead and the shadow retreats into the body’… In view of all this, what we now call ‘high noon’ was thought to be a time of great mana (spiritual power).”  While this passage has be cited by some writers to suggest that “kau ka lā i ka lolo” is thus the traditional Hawaiian term for the ‘zenith sun,’ the phrase seems to refer to “high noon” on any day, and not specifically to those two days a year when the sun is exactly overhead. Thus, in Honolulu on May 23 at 12:28 p.m., one can certainly use the term “kau ka lā i ka lolo” to describe the sun’s position as it sits exactly overhead. However, that same expression “kau ka lā i ka lolo “can be used to describe the sun’s position on any other day at local noon (at least for the non-winter months, when the sun is quite high in the sky at local noon), and does not specifically refer to the phenomenon of ‘zenith noon’ itself.
The chart below gives the overhead sun dates for several locations.The chart below gives the overhead sun dates for several locations.
2018 Lāhaina Noon days and times
|Līhue||May 31 12:35 p.m.||July 11 12:43 p.m.|
|Kāne‘ohe||May 27 12:28 p.m.||July 15 12:37 p.m.|
|Kaunakakai||May 25 12:24 p.m.||July 17 12:34 p.m.|
|Lāna‘i City||May 24 12:24 p.m.|
|Lahaina||May 24 12:23 p.m.||July 18 12:32 p.m.|
|Kahului||May 24 12:22 p.m.||July 18 12:32 p.m.|
|Hana||May 23 12:22 p.m.||July 18 12:30 p.m.|
|Hilo||May 18 12:16 p.m.||July 24 12:26 p.m.|
|Kailua-Kona||May 18 12:20 p.m.|
|South Point Island of Hawai‘i||May 14 12:19 p.m.||July 27 12:28 p.m.|
Honolulu and Kailua-Kona will not experience an absolute Lāhaina Noon this year. The closest the two get is 89 degrees and Lāhaina Noon occurs at 90 degrees.