Annual Astronomy Highlights

Annual Astronomy Highlights

Every year Bishop Museum’s J. Watumull Planetarium 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 Hawai‘i Standard Time (HST). We’ve adjusted all times and dates on our calendar to reflect when they occur in HST.

Bishop Museum also provides the dates and times for lāhainā noon for many locations in Hawai‘iLāhainā noon is the term for the two days each year when the sun is exactly overhead and upright smooth objects cast no shadow. This only occurs in the tropics, and the dates vary depending on latitude. View dates and times here.

In addition to this yearly overview, Bishop Museum provides star maps for each month of the year for Hawai‘i‘s latitudes. These are available on the star map resource page here.

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 every 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.

January 3–4, 2020

Quadrantids Meteor Shower Peak

The Moon will be out until about 1:30 a.m. and is a waxing gibbous, so its light will impact visibility.

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.

January 4, 2020

Earth at Perihelion

This occurs at 9:47 p.m. on January 4, 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 10, 2020

Penumbral Lunar Eclipse (not visible from Hawaiʻi)

This one will not be visible in Hawaiʻi, unfortunately, because our side of Earth will be facing the Sun as the eclipse occurs. A lunar eclipse occurs when the Moon passes through the Earth’s shadow cast into space by light from the Sun. Lunar eclipses only occur during the full moon phase because that is when the Sun, Earth, and Moon are in a line. This does not occur every full moon because the Moon’s orbit is tilted by about 5o in relation to Earth’s orbit around the Sun, so it is usually above or below the shadow cast by Earth. Occasionally things line up just right so that the Moon passes through the Earth’s shadow, or umbra. This causes a total lunar eclipse. The edge of the umbra is called the penumbra; sometimes during a lunar eclipse the Moon just passes through the penumbra like it does for this occurrence. A penumbral lunar eclipse looks very much like a normal full moon because it’s not passing through the darkest part of the shadow. More info here: https://www.timeanddate.com/eclipse/penumbral-lunar-eclipse.html

January 25, 2020

Chinese New Year

Chinese New Year occurs two new moons before the first day of spring, which occurs on March 19 this year.

There are no astronomy highlights relevant to Hawai‘i in February 2020.

March 10, 2020

Supermoon and Full Moon

This supermoon is the first of two in 2020. The second is on April 7. The Moon will be a little closer to Earth than average for a Full Moon, and thus will appear 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, allowing for observers on Earth to receive the maximum sunlight reflected off the Moon, illuminating its whole disk.

Supermoon background—The term “supermoon” is a recent invention and has received a fair amount of media attention in the last few years. It 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 just a full moon that occurs on 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. Incidentally, there are two super new moons in 2020: on October 16 and November 14.

 

March 8, 2020

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 19, 2020

March Equinox; Northern Hemisphere Spring Begins

At 5:49 p.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 farther 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. The Latin word aequus means equal, and nox means night.

April 7, 2020

Supermoon and Full Moon

The second of two super full moons in 2020. See the March 10 entry above for a supermoon explanation.

 

April 21–22, 2020

Lyrid Meteor Shower Peak

The Moon won’t rise until 6:08 a.m. on April 22, so observing conditions the night of April 21 will be ideal.

The Lyrids are named for the constellation Lyra, the Harp, where they appear to originate from. As with all meteor showers the best viewing times for the Lyrids will be from 12:01 a.m. to dawn (5:45 a.m.), early on April 22. They should start being visible around 10 p.m. while Lyra rises in the east. The shower is active from April 16–25, so if you miss the peak the night of the 21st you may still spot a few in the days before and after. 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.

May 4–5, 2020

Eta Aquarid Meteor Shower Peak

The Moon rises at 4:30 p.m. in the evening of May 4 as a nearly full moon, making for less than ideal meteor watching conditions.

Though this meteor shower’s peak is from May 4–5, it is active from April 19 to May 20 each year. The portion of Aquarius from which the meteors radiate rises above the horizon around 3:00 a.m. This is a light shower of about 20 to 40 meteors per hour. One of its claim to fame: this shower is one of two showers caused by debris from Halley’s Comet, along with the Orionids in October.

June 5, 2020

Penumbral Lunar Eclipse

Unfortunately, this eclipse will not be visible in Hawaiʻi because our side of Earth will be facing the Sun as the eclipse occurs. A lunar eclipse occurs when the Moon passes through the Earth’s shadow cast into space by light from the Sun. Lunar eclipses only occur during the full moon phase because that is when the Sun, Earth, and Moon are in a line. This does not happen every full moon because the Moon’s orbit is tilted by about 5o in relation to Earth’s orbit around the Sun, so it is usually above or below the shadow cast by Earth. Occasionally things line up just right so that the Moon passes through the Earth’s shadow, or umbra. This causes a total lunar eclipse. The edge of the umbra is called the penumbra; sometimes during a lunar eclipse the Moon just passes through the penumbra, as it does on June 5, 2020. A penumbral lunar eclipse looks very much like a normal full moon because it’s not the darkest part of the shadow. More info here: https://www.timeanddate.com/eclipse/penumbral-lunar-eclipse.html.

 

June 20, 2020

June Solstice

Summer begins on June 20 at 11:43 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 officially occurs at 11:43 a.m. HST, because that is when the Sun is directly overhead at the Tropic of Cancer (23° 30ʹ 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 equinox in late September.

 

June 21, 2020

Annular Solar Eclipse (not visible in Hawaiʻi)

This eclipse will not be visible in Hawaiʻi, unfortunately. A solar eclipse occurs when the Moon passes between Earth and the Sun and thus can only occur during the new moon phase. The Moon casts its shadow on Earth and if you are standing on Earth in the Moon’s shadow, the Sun is at least partially blocked by the Moon. The distance from the Moon to the Earth changes during the Moon’s monthly orbit around the Earth. If the Moon is near its closest to the Earth (perigee), the whole disk of the Sun is blocked, and a total solar eclipse occurs. This is because near perigee, the Moon and Sun appear about the same size from Earth’s perspective. Really, the Sun is MUCH larger, about 400 times the Moon’s diameter, but also about 400 times farther away, causing the illusion of being about the same size in the sky when viewed from Earth. Quite an amazing cosmic coincidence! If the Moon is at a farther distance the apparent size of the Moon is not large enough to cover the whole Sun, so a ring of the Sun is visible around the edge of the Moon. This ring is where the word annular, or ring shaped, comes from. Annulus is Latin for ring.

July 4, 2020

Earth at Aphelion and Penumbral Lunar Eclipse

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.

A penumbral lunar eclipse will occur on July 4, but will not be visible from Hawaiʻi. See the June 5, 2020, entry for explanation.

 

July 13, 2020

Jupiter at Opposition

The planet Jupiter is brighter than at 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 the 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.

 

July 20, 2020

Saturn at Opposition

As with Jupiter in June, Saturn shines at its brightest as it hits opposition on July 20. 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.

August 11–12, 2020

Perseid Meteor Shower Peak

The Moon will rise at 12:25 a.m., shortly after the constellation Perseus, for which the shower is named, rises above the horizon. While only half illuminated, it will cause reduced visibility.

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 Perseids are the most famous and bountiful meteor shower with up to 100 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.

September 22, 2020

September Equinox; Autumn begins in the Northern Hemisphere

At 3:30 a.m. the Sun crosses the celestial equator (Earth’s equator projected into space) as its path across the sky (the ecliptic) appears to move farther 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. The Latin word aequus means equal, and nox means night.

October 7–8, 2020

Draconid Meteor Shower Peak

In Hawaiʻi, the constellation Draco, for which the Draconid Meteor Shower is named, sets at about midnight in early October due to our low latitude. This means the meteors will be most active for us from after sunset until about midnight. While the Draconids have produced some spectacular showers in the past, it is typically not among the more impressive meteor showers. The shower is caused by debris from comet 21P/Giacobini-Zinner.

 

October 20–21, 2020

Orionid Meteor Shower Peak

The Moon sets at 9:52 p.m. and the constellation Orion rises at about 10:00 p.m. Visibility should be excellent 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 20 and 21. Like the Eta Aquarids in May, this meteor shower is caused by debris from Halley’s Comet.

 

October 31, 2020

Blue Moon

This is the second full moon of October, so it is called a Blue Moon. It is also a micro full moon because it occurs as the Moon is at its farthest point from Earth in its monthly orbit, called apogee.

November 1, 2020

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.

 

November 16–17, 2020

Leonid Meteor Shower Peak

The Moon sets at 7:35 p.m. on November 16, meaning it will not interfere with meteor viewing. As with all showers, the best viewing is after midnight until dawn, but some meteors could be visible before then.

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. This year is not expected to produce more than 15 to 20 meteors per hour.

December 13–14, 2020

Geminid Meteor Shower Peak

Luckily this year the Moon will be in its new moon phase, meaning it rises and sets with the Sun. A moonless night should make for excellent viewing!

The Geminids are one of the best showers to view, 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.

 

December 14, 2020

Total Solar Eclipse (not visible in Hawaiʻi)

While not visible in Hawaiʻi, this total solar eclipse will see the Moon’s shadow move across southern Chile and Argentina. A solar eclipse occurs when the moon passes between Earth and the Sun and thus can only occur during the new moon phase. The Moon casts its shadow on Earth and if you are standing on Earth in the Moon’s shadow, the Sun is at least partially blocked by the Moon. The distance from the Moon to the Earth changes during the Moon’s monthly orbit around the Earth. If the Moon is near its closest to the Earth (perigee), the whole disk of the Sun is blocked, and a total solar eclipse occurs, like this one. This is because near perigee, the Moon and Sun appear about the same size from Earth’s perspective. Really, the Sun is MUCH larger, about 400 times the Moon’s diameter, but also about 400 times farther away causing the illusion of being about the same size in the sky when viewed from Earth. Quite an amazing cosmic coincidence! If the Moon is at a farther distance, the apparent size of the Moon is not large enough to cover the whole Sun, so a ring of the Sun is visible around the edge of the Moon. This is called an annular eclipse. The word annular comes from the Latin annulus, meaning ring.

 

December 21, 2020

December Solstice

Winter begins on December 21 at 12:02 a.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 occurs officially at 12:02 a.m. HST, because that is when the Sun is directly overhead at the Tropic of Capricorn (23° 30ʹ 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.

 

December 21, 2020

Conjunction of Jupiter and Saturn

On this date, Jupiter and Saturn will appear very close to one another as viewed from Earth. The actual time of conjunction is 3:34 a.m. HST. Unfortunately, at that time the two planets will not be visible in our skies. You can, however, still get a good look at them very close together in the early evening of December 20 and 21. Look west after sunset around 6:00 p.m. until the planets set at about 8:00 p.m. A decent pair of binoculars should give a nice view.

A conjunction is when two or more planets share the same right ascension, or east-west position in the sky. Right ascension is a lot like longitude on a map of Earth but projected onto the sky. Declination, which is like latitude, describing north-south position, is the other axis of the celestial sphere. Just as you can find any location on Earth using coordinates of latitude and longitude, you can find anything in the sky using right ascension and declination. The planets all orbit the Sun along roughly the same plane, so they appear more or less along the same line across the sky as viewed from Earth. This line is also the path the Sun moves [follows?] across our sky and is called the ecliptic. Jupiter and Saturn will appear very close together during their conjunction, but only from our viewpoint here on Earth. In reality, the planets are hundreds of millions of miles apart. At this time Jupiter is 473 million miles from the Sun and Saturn is 928 million miles from the Sun.

 

December 21–22, 2020

Ursid Meteor Shower

The Moon will be out and just past the first quarter phase until about 1 a.m. The Ursids are named for the constellation Ursa Minor, which is in the north part of the sky and is where the meteors appear to originate from. Typically only about 10 meteors per hour are visible from the Ursids. The source of this shower is comet 8P/Tuttle.

About the Planetarium

Bishop Museum’s Jhamandas Watumull Planetarium was the first planetarium in Polynesia. Originally called the Kilolani Planetarium, the Watumull Planetarium has served over six million visitors and students since it opened its doors on December 11, 1961. Our Chronos II star machine provides one of the most vivid, realistic recreations of the night sky available today, with 8,500 pinpoint stars and realistic, bright planets. Our Digistar full dome video system covers the entire dome in immersive video, allowing us to fly through the rings of Saturn or into the depths of the Orion nebula.

The planetarium has 70 seats and serves 70,000 people a year. The planetarium focuses on programs about Hawai‘i; a hallmark of its programs is the blending of live and prerecorded elements within each program.