The seeing was terrible, but at least we could see the Sun while much of the island was overcast and raining. I had hoped to set up in the parking lot for Puʻukohala Heiau but arrived a few minutes after they closed the gate. Instead I set up just below at Spencer Beach park.
Of course the telescope drew a crowd of folks who wanted a look. No matter, an eclipse is a slow motion affair with plenty of time to share the eyepiece. I showed my guests how to take photos with their cell phones at the eyepiece, so everyone got a photo or three of the event.
The solar eclipse of March 8th, 2016 taken from Spencer Beach State Park. Celestron C8 with a Canon 6D at cassegrain focus, 2000mm focal length
A partial solar eclipse from Kawaihae, 9 May 2013Just a reminder that later today there will be a solar eclipse. This is a total with the path of totality passing north of the main Hawaiian Islands near Midway. For the Big Island this will be a deep partial, about 55%.
The 1999 Total Solar Eclipse from France, image credit Luc ViatorThe 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.
Diagram of the March 9, 2016 Total Solar EclipseThere 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.
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.
A partial solar eclipse from Kawaihae, 9 May 2013Observing 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.
Looking ahead to sharing a fun and pretty 2016 with everyone. As usual you can come to Darker View for heads up on everything happening in the sky for 2016. I have spent the last month setting up pre-scheduled posts with all of the significant sky events for the year. We have a couple interesting eclipses, including a total eclipse across the Pacific, and some nice conjunctions. Comet C/2013 US10 Catalina continues to be naked eye into January and C/2013 X1 PanSTARRS should be marginally naked eye in June.
A very young moon over Waikoloa, this is only 26 hours after new, visible to the unaided eye as a sliver in the fading glow of sunsetSetting up all of the scheduled astronomy posts for the year allows me an excellent overview of what the coming year will bring. As I go though the schedules I have assembled a summary here to give my readers a preview of the year and to allow advance planning.
The Moon
Below are tables of all of the new and full moons of 2016 for those who prefer to plan early for those observing outings. Eclipses are noted with an asterisk in the tables and are explored more fully in the following section.
For those who like supermoons you will have to wait for later in the year when the orbit and lunar phase align. November will be the best supermoon of the year when full moon occurs only two hours away from perigee on the 14th of the month. For a few months either side of the November full moon you will find perigee occurring within a day or two of full, allowing for larger and brighter than average full moons. Continue reading “The Sky for 2016”
One of the more sublime sights seen from Mauna Kea is the shadow of the mountain rising through the mist and haze at sunset. One of the more sublime sights in the heavens is the Earth’s shadow crossing the face of the Moon, a total lunar eclipse. It is possible to combine these two phenomena if the timing is right, the Earth’s shadow seen twice.
The eclipsed moon rising in the shadow of Mauna Kea, February 20, 2008, photo by Alex Mukensnable, used with permissionThe moment of totality in a lunar eclipse occurs when the full Moon is directly opposite the Sun in the sky. By simple geometry this same anti-solar point is where the tip of the mountain’s shadow will be projected for an observer standing near the summit of the same mountain. If the eclipse is in progress at sunset, and you are standing on the summit of a suitably prominent mountain, you will see the Earth’s shadow both in the sky and obscuring the Moon.
Back on Feb 20th, 2008 the timing was right. A friend of mine, Alex Mukensnable, noted the timing and set up to catch the eclipsed Moon rising in the shadow. The result was a great set of photos. The photo is nice enough as a still, be he did more than that, he shot the event as a timelapse and assembled a video of the rising Moon.
There are several possible variations depending on the timing with this sort of event… If the Moon was at the height of totality rising it would also be right at the tip of the mountain shadow as it rises. This is a relatively rare event as the timing requirements are tight. Unfortunately it would also be quite dim, darkened by the shadow, and not easily seen as it rose.
As lunar eclipses are long events, taking several hours to complete, the likelihood of the Moon being in at least the partial eclipse phase at sunset is fairly good. Still a rare event, but not extraordinarily so. Thus for a single site, the summit of Mauna Kea this even happens in both 2008 and 2015.
As the Earth’s shadow is about 2.6° across at lunar orbit, the closest a partially eclipsed Moon will be seen from the the very tip of the shadow is about 1.3°. This is a bit less than three lunar diameters. Of course these numbers will vary a few percent depending in the distance to the Moon which changes as it makes its elliptical orbit.
The Moon moves slowly across the sky from west to east, thus before totality the Moon would be above the tip of the mountain shadow. After totality, with the eclipse ending, the eclipsed Moon will be in the shadow. Placing the Moon in the shadow also makes it easier to see, the bright crescent a better contrast to the dark shadow. This is the case for the 2008 eclipse captured by Alex.
Of course you could reverse all this timing and watch the event at moonset and sunrise. If the eclipse was just starting at dawn it would again place the eclipse in the mountain shadow.
Another important point to remember is that the shape of the mountain’s shadow has little to do with the shape of the mountain. The shadow will always be a neatly conical form due to the effects of projection.
What brings this event back to the fore is that the timing will soon be correct to see this same event again. The total lunar eclipse of Sept 27th, 2015 will be a bit of a dud for Hawaii, most of the eclipse already over as the Sun sets and the Moon rises over the islands. However, this event will feature very similar timing to the 2008 eclipse. The Moon will still be in partial eclipse when it rises. As it rises a short time after full Moon it will again be deep in the shadow of Mauna Kea as it comes over the horizon.
You know where you will find me on the evening of the 27th. Now I just need some clear weather that day.
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 transiting the face of the Sun, 6 Nov 2006
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.
We have been lucky in the islands lately when it comes to total lunareclipses. A series of total eclipses have been visible from start to end from our vantage point in the middle of the Pacific. There is an average of one eclipse visible per year from any given place, but that is an average, you can go several years without an opportunity. Both 2012 and 2014 have given us two good eclipses and 2015 provides one.
The sum of 699 exposures taken through the lunar eclipse of Apr 4, 2015This eclipse would be a bit different however… Overall the eclipse lasted as long as is normal for a lunar eclipse, about three and a half hours. It was the total phase that was unusually short for this particular eclipse. It was only about four minutes that the moon would be entirely within the umbra, the darkest part of the Earth’s shadow. This usually lasts about an hour. The umbral magnitude of this eclipse was 1.0008, just barely over the threshold of one that designates a total lunar eclipse.
On Friday I did a quick interview with a reporter from the West Hawaii, Today, our local newspaper. He was looking for a little more information on the eclipse and a somewhat more local angle than a wire article on this eclipse. I chatted for a while, and got written up in the article…
The total lunar eclipse on Apr 14, 2014, Canon 6D on 90mm f/12 APOEarly tomorrow morning a total lunar eclipse will be visible across the Pacific. Sky watchers in Hawaiʻi will be able to observe this event from beginning to end.
