2019 Astronomy Highlights
2019 Astronomy Highlights
Every year Bishop Museum’s J. Watumull Planetarium (Honolulu, Hawai‘i) provides a calendar of astronomical events specifically for Hawaiʻi’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. We’ve adjusted all times and dates on our calendar to reflect when they occur in Hawaiʻi Standard Time.
This calendar also provides the dates and times for “Lāhainā Noon ” for many locations in the islands. Lāhainā 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 Hawaiʻi’s latitude. This resource is available on the Bishop Museum Planetarium website: www.bishopmuseum.org/planetarium.
January 2, 2019
Earth at Perihelion
This occurs at 7:20 p.m. on January 2, Hawaiʻi Standard Time. On this day, Earth is only 91.4 million miles from the Sun, compared to an average distance of 93 million miles. (At aphelion, in July, Earth will be 94.5 million miles from the Sun).
Like all planets, Earth’s orbit is not a perfect circle but is elliptical, or like 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, although 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.
January 20, 2019
Total Lunar Eclipse, Supermoon, and Full Moon
In the early evening hours of this day, just after sunset, a lunar eclipse will be visible. Since the maximum for the eclipse is so soon after it rises, you’ll want to be sure you are somewhere with a clear view of the eastern horizon. (Maximum is when the Moon is entirely in the Earth’s shadow.) At 7:12 p.m., when the eclipse is at maximum, the Moon will be only about 13 degrees above the horizon. For reference, an adult’s clenched fist held at arm’s length straight out in front spans about 10 degrees. Point at the horizon with your whole hand, then make a fist with little finger on bottom and thumb on top.
Lunar eclipses can only happen during a full moon. They occur two to four times 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 shadow, called the umbra, and can turn the Moon to an eerie shade of blood red. For Hawaiʻi, this lunar eclipse will begin while the Moon is still below our horizon. The Moon rises at 6:07 p.m. and full eclipse begins at 6:41 p.m. It will reach maximum at 7:12 p.m., with full eclipse ending at 7:43 p.m. The partial eclipse ends at 8:50 p.m. and the whole event ends at 9:48 p.m. The following is the timing breakdown for different parts of the eclipse from timeanddate.com:
Partial umbral eclipse begins: Moon below horizon
Moonrise: 6:07 p.m. HST
Total eclipse begins: 6:41 p.m. HST
Greatest eclipse: 7:12 p.m. HST
Total eclipse ends: 7:43 p.m. HST
Partial umbral eclipse ends: 8:50 p.m. HST
This supermoon is the first of three in 2019. 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 from us 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 larger and a little brighter than a “normal” full moon.
The astronomer 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 in “super new moons” since you cannot see a new moon.
February 5, 2019
Chinese New Year
Chinese New Year occurs two new moons before the first day of spring, which occurs on March 20 this year.
February 19, 2019
The second of three supermoons in 2019. This one will be the biggest and brightest of the three. See January 20 entry above for a supermoon explanation.
March 10, 2019
Daylight Saving Time Starts for US Continent
Start of Daylight Saving Time for most of the 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.
March 20, 2019
March Equinox; Northern Hemisphere Spring Begins
At 11:58 a.m. HST, the Sun crosses the celestial equator (Earth’s equator projected into space) as its path across the sky (the ecliptic) appears to move further north. On this day the Sun rises due east and sets due west and the length of day and night are approximately equal. The equal day and night is where the word equinox comes from. Aequus in Latin means equal and nox means night.
March 21, 2019
The third and final supermoon of 2019. See January 20 entry above for a supermoon explanation.
June 10, 2019
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, Earth, and the other planet, with Earth being in the middle. This allows for maximum reflection of sunlight from the planet to bounce back to us on Earth. 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.
June 21, 2019
Summer begins on June 21 at 5:54 a.m. HST for the Northern Hemisphere. This day has the most hours of sunlight of the year for the Northern Hemisphere and the fewest for the Southern Hemisphere. The solstice is officially at 5:54 a.m. HST because that is when the Sun is directly overhead at the Tropic of Cancer (23o 30′ N Latitude). The sun will rise at its point farthest north of east and will set at its farthest north of west. After this day the Sun will rise and set closer and closer to due east and west heading toward the autumnal equinox in late September.
July 4, 2019
Earth at Aphelion
At 12:10 p.m. HST the Earth will be 94.5 million miles from the Sun, the farthest point in its orbit.
Like all planets, Earth’s orbit is not a perfect circle but rather an oval. Earth reaches aphelion, its farthest point from the Sun, in early July 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 is the tilt of the Earth. Each July, although we are farther from the Sun than at any other time of the year, the Northern Hemisphere is tilted toward the Sun, receiving more direct sunlight, and so we experience summer.
July 9, 2019
Saturn at Opposition
As with Jupiter in June, Saturn shines at its brightest as it hits opposition on July 9. There is a straight line between the Sun, Earth, and Saturn. The ringed planet rises at sunset, is overhead all night, and sets at dawn.
September 22, 2019
September Equinox; Autumn begins in the Northern Hemisphere
At 9:50 p.m. the sun crosses the celestial equator (Earth’s equator projected into space) as its path across the sky (the ecliptic) appears to move further south. On this day the Sun rises due east and sets due west and the length of day and night are approximately equal. The equal day and night is where the word equinox comes from. Aequus in Latin means equal and nox means night.
November 3, 2019
Daylight Saving Time Ends
Daylight Saving Time ends at 2 a.m. for most of the 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.
December 21, 2019
Winter begins on December 21 at 6:19 p.m. HST for the Northern Hemisphere. This day has the least hours of sunlight of the year for the Northern Hemisphere and the most for the Southern Hemisphere. The solstice is officially at 6:19 p.m. HST, because that is when the Sun is directly overhead at the Tropic of Capricorn (23o 30′ S Latitude). The Sun will rise at its point farthest south of east and will set at its furthest south of west. After this day the sun will rise and set closer and closer to due east and west heading toward the vernal equinox in late March.
For all meteor showers, the viewing will be better after midnight. This is because after midnight, the part of the Earth that you are on faces toward the debris that causes the meteor shower.
These repeating annual events are caused as the Earth enters into a field of 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.
Meteor showers are named for the constellation where the meteors appear to come from. The Lyrid shower is named for the constellation Lyra the Harp, for example. 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 meteors.
To view meteor showers, just find a dark location (with as little city light as possible), get comfortable (a lawn chair is a good idea), and look up.
Quadrantid Meteor Shower
Peak night: January 3–4, 2019
The Moon will be a waning crescent and sets at 4:30 p.m. on January 3. This means we’ll have a moonless night to watch this shower!
The Quadrantids have a sharp, short peak, lasting only a few hours. The streaks of the Quadrantids appear to come from the constellation of Boötes (Boo-oh-tees) the Herdsman, in the northeast. “Quadrant Muralis,” or “Mural Quadrant,” is an old name for part of the constellation of Boötes. This is 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.
Peak night: April 22–23, 2019
The Moon rises at about 10:30 p.m. on April 22, so it will be out all night. While not full, it is still a waning gibbous moon and will wash out enough of the sky that visibility of meteors will be less than ideal.
The best viewing times for the Lyrids will be from 12:01 a.m. to dawn (5:45 a.m.), early on April 22, and from 12:01 a.m. to dawn, early on April 23. 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 are generated from the debris of Comet C/1861 G Thatcher.
Peak night: May 5–6, 2019
The Moon will set at 8 p.m. and will be a very slender crescent, making for exceptional meteor-watching conditions.
Though this meteor shower’s peak is from May 5–6, it is active from April 19 to May 20, 2019. The portion of Aquarius where the meteors radiate rises above the horizon around 3:00 a.m. This is a light shower, 20 to 40 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.
Peak night: August 12–13, 2019
The Moon will be nearly full and will wash out all but the brightest of meteors. It does set at 4:30 a.m., so from 4 a.m. until dawn begins at 5:45 a.m. will be the best time to watch.
This meteor shower is active from July 13 to August 26, but the most active and fruitful dates of this shower are August 12 and August 13. The Perseids are the most famous and bountiful meteor shower with up to 80 meteors per hour, often leaving long trails across the sky. The shower is generated by debris from Comet 109 P Swift Tuttle. This comet takes 130 years to orbit the Sun. It most recently passed through the Earth’s part of the solar system back in 1992, leaving lots of fresh comet debris that leads to particularly good showers.
Peak night: October 21–22, 2019
The Moon will be a waning crescent just past last quarter, but will be bright enough to impact visibility. It rises about midnight and will be up all night.
The active period for this shower is September 23–November 27, though the peak, producing about 20–25 meteors an hour, will be on October 21 and 22. Like the Eta Aquarids in May, this meteor shower is caused by debris from Halley’s Comet.
Peak night: November 17–18, 2019
The Moon will rise at 10:45 p.m. The fact that it will be very close to the constellation Leo makes visibility poor this year.
The Leonids have an intense peak every 33 years and were responsible for the greatest meteor shower over Hawaiʻi in recent times—the 2001 shower. Prior to that 2001 spectacle, the 1966 shower was one of the greatest on record.
Peak night: December 14–15, 2019
The Moon will be a bright waning gibbous, very near the radiant of the Gemini constellation, impacting visibility.
The Geminids are one of the best showers as the meteors are very bright and intensely colored. We in Hawaiʻi are lucky as we 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.
|New Moon||First Quarter||Full Moon||Last Quarter|
|January 5||January 13||January 20||January 27|
|February 4||February 12||February 19||February 26|
|March 6||March 14||March 20||March 27|
|April 5||April 12||April 19||April 26|
|May 4||May 11||May 18||May 26|
|June 3||June 9||June 16||June 24|
|July 2||July 9||July 16||July 24|
|July 31||August 7||August 15||August 23|
|August 30||September 5||September 13||September 21|
|September 28||October 5||October 13||October 21|
|October 27||November 4||November 12||November 19|
|November 26||December 3||December 11||December 18|
In the tropics (between latitudes 23o 26′ N and 23o 26′ S) the Sun passes directly overhead twice during the year. On these two days, at local noon, the Sun will be exactly overhead and an upright objects such as a flagpole 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 11, at 12:43 p.m. Farther south, on the island of Hawai‘i, the overhead sun date occurs on July 24 (12:27 p.m. for Hilo, 12:31 p.m. for Kailua, Kona).
Here in the Islands a term we often use for zenith noon is Lāhainā 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.
The chart below gives the overhead sun dates and times for several locations.
|Līhuʻe||May 31, 12:35 p.m.||July 11, 12:43 p.m.|
|Haleʻiwa||May 28, 12:30 p.m.||July 14, 12:38 p.m.|
|Kāne‘ohe||May 27, 12:28 p.m.||July 16, 12:37 p.m.|
|Honolulu||May 27, 12:29 p.m.||July 16, 12:38 p.m.|
|Kaunakakai||May 26, 12:25 p.m.||July 17, 12:34 p.m.|
|Lāna‘i City||May 24, 12:25 p.m.||July 19, 12:34 p.m.|
|Lahaina||May 24, 12:24 p.m.||July 19, 12:33 p.m.|
|Kahului||May 24, 12:23 p.m.||July 19, 12:32 p.m.|
|Hāna||May 23, 12:21 p.m.||July 19, 12:30 p.m.|
|Hilo||May 18, 12:17 p.m.||July 24, 12:27 p.m.|
|Kailua, Kona||May 18, 12:20 p.m.||July 24, 12:31 p.m.|
|South Point, Hawai‘i Island||May 15, 12:19 p.m.||July 28, 12:29 p.m.|