Tag: solar

On March 9, 2016 a total solar eclipse will sweep across Indonesia and into the central Pacific. This will be an late afternoon eclipse, with maximum occurring just before sunset at around 17:37 HST (5:37pm HST).

The path of totality passes well north of the Hawaiian Islands, just south of Midway Island. If you want to see this eclipse as a total your best bet is an eclipse cruise. For the islands this will be a deep partial eclipse, ranging from about 67% for Kauai and the around 55% for the Big Island. Of course, the exact amount of the Sun covered by the Moon will depend greatly on your location. See the table below for predictions and timing for your location.

Note, you might be confused by some references that state the eclipse occurs on March 9th. It does occur on the 9th! For our islands greatest eclipse occurs around 03:30 on March 9th universal time. If we convert to Hawaiian Standard Time this will be the 17:30 (5:30pm) on the afternoon of March 8th. You must remember that universal time is ten hours ahead of Hawaiian Standard Time.

There are several cruises scheduled to intercept this eclipse. Most look to observe the eclipse somewhere near Indonesia, where the eclipse will be at its maximum. This is where you will find the hardcore eclipse chasers, including a few island folks I know. Most of us will just have to settle for seeing this eclipse as a partial, including myself. The information presented here covers viewing the eclipse from the islands.

A deep partial can be very interesting. Even people not expecting the eclipse may notice a dimming of the Sun and an odd, subdued nature to the sunlight. Even a quick glimpse of the Sun will reveal that half of the disk is covered. Eclipse glasses or a welding filter will provide a nice image of a partially eclipsed Sun. Tree leaves and other makeshift pinhole cameras will show crescent images of the Sun on the ground. For best viewing a small telescope with a solar filter, or a pinhole camera will allow excellent images of the eclipse. My standard eclipse viewing setup is a 76mm refractor with a Baader film solar filter. I assembled this gear for the 2012 Venus transit and it has seen several eclipses since.

Solar Eclipse Data for March 8th, 2016
	Mag	Begin	Max	End
Hilo	55%	16:37	17:37	18:32
Honolulu	63%	16:33	17:36	18:33
Lihue	67%	16:31	17:35	18:33
Kahului	60%	16:35	17:37	18:33
Kona	56%	16:36	17:37	18:32
Mauna Kea	56%	16:37	17:37	18:32
Midway Is	97%	16:04	17:20	18:29
All times HST
Source: EclipseWise Interactive Map

The table at the right gives the eclipse timing for a few locations across the Hawaiian Islands. All times are given in Hawaiian Standard Time, just remember that 17:36 is 5:36pm in 12 hour time, just subtract 12.

As you can see the magnitude of the eclipse increases notably the closer you are (further north in the main islands) to the path of totality. The timing does not vary by nearly as much, with maximum eclipse occurring around 17:36 for the islands.

If you would like to see precise information for your location, or for someplace other than the islands, just use the interactive map and click on your location for data.

Observing a partial solar eclipse requires proper eye protection. If you can not look safely, do not look! Even dimmed by 50% or more the Sun can cause permanent eye damage if viewed without proper protection. A solar filter is required for telescopic or binocular use. A good view can be had without magnification simply using a welding filter (shade 13 or darker) or solar viewing glasses to look directly at the Sun. A pinhole camera can be made out of things lying around in your kitchen that provides a very good image. Read my Guide to Safe Solar Viewing for a lot more information on viewing the Sun safely.

There are no further solar eclipses near the Hawaiian islands until 2031 and 2035, the path of totality for both of which pass well south of the main islands. There is also an annular eclipse in 2024, for which the center line also passes well south of the islands.

On May 9th, 2016 Mercury will transit the Sun. While transits of Mercury are not rare, they are not all that common either. The last transit was almost a decade ago in November of 2006. On average there are fourteen transits of Mercury each century or one every seven years. If you wish to observe one the situation is much better than transits of Venus which occur in pairs over a century apart.

This particular transit will favor observers in Europe and North America where the entire transit will be visible. Unfortunately for observers in the islands only the final three hours of the transit will be visible having begun well before local dawn. Sunrise will occur around 05:48 for the island of Hawaiʻi, with the transit ending at 08:42 in the morning.

Mercury Transit May 9th, 2016
	UT (geo)	HST	HST (offset)
First Contact	11:12	01:12	–:–:–
Second Contact	11:15	01:15	–:–:–
Greatest	14:57	04:57	–:–:–
Third Contact	18:39	08:39	08:39:58
Fourth Contact	18:42	08:42	08:43:10
Source: NASA Eclipse website

The table at the right gives the transit geocentric UT and offset HST times. As our line of sight is shifted slightly from Hawaii there is a slight offset in the timing from our vantage point.

First contact is simply the first moment that the disk of Mercury begins to impinge on the disk of the Sun. Second contact will be the moment when Mercury is entirely in front of the Sun. Third and fourth contacts are a reverse of first and second with fourth contact as the end of the event.

Observing a planetary transit of the Sun requires proper eye protection. If you can not look safely, do not look! The Sun can cause permanent eye damage if viewed without proper protection. As Mercury is quite small some magnification will be useful in observing this event, a telescope of binoculars with a solar filter. A pinhole camera can be made out of things lying around in your kitchen that provides a very good image. Read my Guide to Safe Solar Viewing for a lot more information on viewing the Sun safely.

The next transit of Mercury will occur November 11, 2019 at 15:20UT (mid-transit). This next transit also favors Europe and eastern North America where the entire transit will be visible.