Partial eclipse to take bite from sun over isles March 8

We will have a deep partial solar eclipse in Hawaii on the afternoon of March 8 when the moon passes between Earth and the sun and blocks part of the sun’s disk.

Beginning at 4:33 p.m., using safe viewing techniques, you will see a small “bite” taken out of the sun as the moon begins to move in front. The bite will seem to deepen over the next hour. At the eclipse’s peak, at 5:37 p.m., about 70 percent of the sun will be blocked by the moon.

By that time, the sun will be low in the sky, only 14 degrees above the west horizon; that’s about 1.5 hands held at arm’s length. The eclipse ends at 6:33 p.m., just a few minutes before the sun sets at 6:36 p.m.

You must have a clear view of the west to see this eclipse, since the sun will be low in the afternoon sky.

An important note: It is never safe to view a partial solar eclipse directly. The inexpensive, safe viewing glasses carried by Bishop Museum’s Shop Pacifica and other venues are a good means of viewing solar eclipses. (These glasses retail for $2 at Shop Pacifica. I recommend getting them early, since we sell out of them every time we have a major solar event.)

Partial versus total eclipses

Because the sun is so bright, you will not notice a change in the brightness of the sun during a partial eclipse, even when more than two-thirds of the sun is blocked by the moon. So on March 8, most folks will have no idea an eclipse is occurring unless they are viewing the sun through a safe filter. The eerie sensation of “darkness in the daytime” only occurs during a total eclipse of the sun, when the moon briefly blocks out the entire solar disk; this is a much rarer phenomenon for any one spot on Earth than a partial eclipse.

Any given spot on Earth sees a partial solar eclipse every few years; our last one in Hawaii was on May 9, 2013, and the next occurs at dawn on Aug. 21, 2017. Any given spot on Earth sees a total solar eclipse only, on average, once every 360 years; our last total solar eclipse (over the island of Hawaii) occurred on July 11, 1991, and the next total eclipse over a Hawaiian island does not occur until 2106.

So Hawaii residents who want to see a total solar eclipse — the most awesome sight in astronomy — will have to travel. The partial eclipse in Hawaii in 2017 will be a total eclipse on that same day across the heart of the mainland U.S., with the city of Nashville in the path of totality. If you want to head for the continent, make your plans soon; hotels are already filling up.

Viewing event

Bishop Museum will host a partial solar eclipse viewing event from 3 to 6:30 p.m. March 8. Volunteers from the Hawaiian Astronomical Society and the Institute for Astronomy will be on the great lawn with their large, safely filtered telescopes to provide views of the eclipse in progress, and the observatory will be open as well.

While both of these viewing events are weather-dependent, we will also feature a webcast of this same eclipse from Micronesia, where it will be total. We will also present eclipse planetarium shows hourly from 3 to 6 p.m., exploring why eclipses occur and previewing both this eclipse and the “Great American Eclipse” of summer 2017.

The eclipse program is included with regular Bishop Museum admission; the museum will remain open until 6:30 p.m. that day.

Planets in March

All month, the brilliant planet of Venus rises just after 5:30 a.m. in the east and is about 10 degrees above the horizon by daybreak 45 minutes later.

Jupiter rises in the east around sunset in early March, is high overhead at midnight and sets in the west at dawn. It is in opposition on March 8, with the sun, Earth and Jupiter in a straight line; during opposition an outer planet generally shines at its brightest. By the end of the month, Jupiter is a third of the way up in the east at dusk, crosses the top of the sky at 11 p.m. and sets in the west at 5 a.m.

In early March, orange Mars rises a little after midnight in the east-southeast and is halfway up in the south at 6 a.m. as it disappears into the breaking day. By late March, Mars rises at 11 p.m., is halfway up in the south at 4 a.m. and high in the west by daybreak. Mars will double in brightness during the month.

Saturn rises in the east at 1:30 a.m. in early March and is due south at daybreak. By the end of the month the ringed planet comes up at 11:30 p.m. and is high in the west at dawn.

While we’ve lost Mercury to the sun’s light all month, the other four naked-eye planets remain in the dawn sky, as they were in February.

At 6 a.m. in early March, look for Venus rising low in the east as Jupiter sets in the west. The two planets are the sky’s brightest dots. Then, look due south; both Saturn and Mars will be halfway up in the southern sky before dawn, Saturn to the left and Mars to the right of due south. Mars is distinctly orange, Saturn white-yellow.

By the end of the month you can still find Venus huddled low in the east and Jupiter low in the west, but you’ll have only a few minutes around 5:50 a.m. to catch Mars and Saturn (high in the west by the end of the month) before daybreak. In the course of the month, the middle two planets in this quartet, Mars and Saturn, appear to draw closer to each other; they are 20 degrees apart in early March (two fists at arm’s length), and only 10 degrees apart at the end.