Solar Events – Page 2 – A Darker View

Safe Transit Viewing

You have heard it before, but it really is true! Looking at the Sun for longer than a few brief moments with an unprotected eye can lead to permanent damage. Looking at the Sun with any sort of optical deceive that has not been properly filtered can lead to instantaneous eye damage.

Discussed below are the only safe methods I am aware of to view the Sun. There are some dodgy methods out there. Take chance with your irreplaceable eyesight? I think not. Be careful and do it right if you want a look.

For the unaided eye there are a couple options to view the Sun safely…

Solar Viewing Glasses Proper solar viewing filters are made from a thin plastic film, usually mylar, coated with metal to properly filter the Sun’s light for viewing with the unaided eye. These are widely available and quite cheap. Local astronomy organizations have been giving them away in preparation for the transit. Do not attempt to use these viewers in conjunction with binoculars or small telescopes, they do not provide sufficient filtering for optics!
Welding Glass Filters used for viewing welding offer much the same protection as solar filters. A shade 13 or darker welding filter can provide good protection for the unaided eye. Again, do not use a welding filter with any sort of optical device such as binoculars, they are not designed for such use and may not block enough light.

A much better view of the event can be seen if modest magnification is used. Do keep in mind that any soft of binoculars or telescope also concentrates much more light that the eye alone. Remember those childhood “experiments” involving a magnifying glass and ants? The best options here are the use of solar filters designed to be used on a telescope, or indirect means such as image projection.

Solar Filter — A solar filter mounted on a refracting telescope

Solar Filters for Telescopes Filters specifically designed for telescopes consist of either a plastic film, or a sheet of glass, coated with a thin layer of metal to block the Sun’s light. These filters pass about 1/1000 of one percent of the light. More importantly, they block the harmful infrared and ultraviolet light that could so easily cause damage. The filters can be purchased in many sizes as appropriate for various models of telescopes, costing between one hundred and several hundred dollars.
Image Projection One of the simplest methods of displaying a solar image is projection. A white screen placed a foot or two behind a telescope will produce a very nice image of the Sun that can be safely viewed by a number of people simultaneously.
Keep in mind that the beam of light out of the eyepiece is quite intense, potentially hot enough to burn a careless finger placed near the exit from the telescope.

The method works best with small optical systems, binoculars or the smallest of telescopes. You do not need big optics to project a very nice solar image.

You do not have any optics? Use the simplest optical arrangement of all, the pinhole camera!

If you do not have a safe means of viewing the transit and do want a look, you can go to one of the many public events being organized. Here on the Big Island there are quite a few options, one should be close to you.

Transit of Venus Timing

For reference I am posting precise transit timing for the June 5th Transit of Venus. The data is taken from Fred Espenak’s wonderful NASA Eclipse Website. I just extracted the cities that are of most interest to my Hawaiian readers. For the full list of US cities you can go here.

As you might notice, the times change by a mere two seconds between Kona and Honolulu. These times will be pretty close for the entire island chain. That last number is the Sun’s altitude, the angle above the horizon. Note that this is near 90° for Hawai’i, nearly straight up for the start of the event. Final contact will occur with an altitude of about 5°, just above the horizon near sunset.

Location Name	External Sun Ingress Alt h m s °	Internal Sun Ingress Alt h m s °	Greatest Sun Transit Alt h m s °	Internal Sun Egress Alt h m s °	External Sun Egress Alt h m s °
Anchorage, AK	14:06:30 51	14:24:04 51	17:26:53 38	20:30:46 16	20:48:32 14
Honolulu, HI	12:10:07 85	12:27:46 89	15:26:20 49	18:26:38 9	18:44:38 5
Kona, HI	12:10:09 86	12:27:48 87	15:26:16 47	18:26:33 7	18:44:33 3
Los Angeles, CA	15:06:26 58	15:24:02 55	18:25:33 18	— –	— –
Phoenix, AZ	15:06:03 54	15:23:40 50	18:25:32 13	— –	— –
Portland, OR	15:06:05 57	15:23:40 54	18:25:53 23	— –	— –
San Francisco, CA	15:06:29 61	15:24:04 57	18:25:39 22	— –	— –
Seattle, WA	15:05:58 56	15:23:32 53	18:25:57 23	— –	— –

All times are local time. Keep in mind that this event occurs on June 5th for viewers in the US and Hawai’i. Some sources show June 6th for a date, and so it will be for viewers on the other side of the date line in Australia, Japan and China.

Preparing for the Venus Transit

Time to start preparing the gear for Venus Transit! This means dismantling the astrophotography rig in the garage and reconfiguring for solar work. Taking the the AT6RC telescope off and remounting the 90mm APO. The APO has just the right focal length to produce a nicely sized solar image on an APC-C sized sensor, such as the sensor in the Canon 60D.

First up? just setup the ‘scope in the driveway and take a few photos of the Sun. Just checking the photographic setup, the necessary parts and pieces. Nothing misplaced? Where did I store the solar filter? A nice focus on the camera? Perhaps take some nice photos of the large sunspots that current grace the surface of the Sun while I am set up. I hope we have some nice spots during the transit, they make focusing so much easier!

Next step is to get autoguiding operational, this will be a seven hour event and I really do not want to manually guide for the entire duration. Particularly with a telescope that was setup in the daytime and is not properly polar aligned.

A couple other steps remain in the preparation. Automate the camera to take photos at a regular interval. Insure I can provide a good video feed to the computer sending out the webcast. I do have a few more weeks to accomplish this. I am certain those weeks with speed by surprisingly quickly. Time to get ready!

Venus Transit on Mauna Kea

A Venus Transit is a truly rare event. Transits occur in pairs eight years apart, with the next pair not occurring for another 120 years. The first event of the current pair occurred in 2004. Thus the next event will happen in June 2012. Considering the century long period between events, this is the last chance to witness a Venus transit during our lifetimes.

The 2012 event will be visible from the west coast of North America to Japan, China, Australia and Central Asia. For those wanting to observe the entire event from start to finish the choices narrow quite a bit. You have the choice of the Central Pacific, Japan, as well as Eastern China and Eastern Australia. This, of course, includes here in the Hawaiian Islands.

Many sky-watchers from North America will see only one choice if they wish to observe the event… the Big Island. The only place easily accessible by air, featuring excellent visitor accommodation, and an observing site that sits above the clouds that could so easily interfere with carefully laid plans. For the serious observer there is one obvious choice… Mauna Kea.

We saw the first signs of this well over a year ago. The tour companies that specialize in astronomy related travel, the folks that feature solar eclipse tours and similar events, began scouting Mauna Kea as a destination. Then the ads appeared, in Sky & Telescope magazine, Astronomy magazine, etc., “See the transit from Mauna Kea!” We had fair warning that this event was not going to pass peacefully.

Visibility chart for the 2012 Venus transit, image credit: Fred Espenak/NASA

Some folks seem to think the crowd will be huge, a thousand people or more. I am not so certain, this does not have the general appeal of a total solar eclipse. The transit is something that will be of interest to amateur astronomers and some interested segments of the public. I personally expect hundreds of people coming to Mauna Kea to view the transit, not thousands.

However many folks do ascend the mountain for this event, we have begun putting plans in place to handle it. Various groups have met to do a bit of planning. Most significantly, those in charge of managing the mountain, The Office of Mauna Kea Management, are putting a few measures in place. As usual, expect to stop at the Mauna Kea Visitor Information Station on the day of the transit. But this day there will be a few differences…

All available MKSS staff will be on duty. All of the Mauna Kea rangers and visitor station staff will be helping make sure assistance is available to visitors when traveling to the high altitude environment of the summit.
Access to the mountain will be controlled for the day, a gate at the VIS allowing access for official vehicles only.
A free shuttle will run from the VIS to the summit. The Mauna Kea tour companies providing the vehicles and drivers.
Solar telescopes and video monitors will be set up at the VIS to allow safe viewing. Staff will be available to answer questions and assists with the equipment.
Several other locations on the island will be setup for viewing the transit with solar telescopes and staff. Expect these to include ‘Imiloa, Keck HQ in Waimea, and some possible other locations.

All of these plans are somewhat preliminary, details may change as the date approaches and final arrangements are made. I will attempt to post what I know here on Darker View.

Myself? I plan to observe the event from the summit. Set up behind Keck with a solar telescope to photograph the transit. We plan to set up a live feed of the transit for use by other sites, and available to viewers across the internet.

Geomagnetic Update

The CME from yesterday’s solar flare struck at about 01:00HST, not as strongly as predicted. Right now there is a geomagnetic storm going on, but only at a moderate intensity, Kp=5. It takes something with a Kp>10 before aurora become a likelihood at low latitudes. Expect some nice photos from the folks up north as they get to enjoy the show.

The sunspot responsible for the flare, AR1429, is still there, pointed directly at our Earth. It harbors the energy for more X class flares, stay tuned!

Sun at 304nm — The Sun at 30.4nm (extreme ultraviolet) on 8Mar2012 showing the large sunspot group AR1429 (upper center), image credit NASA/SDO

Geomagnetic Storm Warning

At 00:28UT March 7th (14:28HST March 6th) our Sun let loose with a X5-class solar flare. This is the largest event in many years, and the impact will be felt here on Earth later today. We can expect a major geomagnetic storm when the mass of charged particles strikes the Earth’s magnetic field sometime around 0625UT (±7hr) on March 8th (2025HST March 7th).

Skywatchers at all latitudes have a chance of seeing aurora.

Yes, this means a chance of seeing aurora here in Hawai’i. I have seen aurora in southerly locations, including Tucson at 32° latitude. It is possible given a strong enough event. Fortunately the tropical storm we have experienced for the last few days appears to be clearing out. I will have to check the northern skies this evening.

The culprit is sunspot group AR1429, an enormous magnetic disturbance on the face of the Sun. An enormous amount of energy stored in the twisted magnetic fields of AR1429 was released when the fields ruptured. The result was a powerful solar flare. This event was recorded by several spacecraft at a number of wavelengths. The resulting imagery and movies are worth checking out.

For updated info on the event you can check in with dedicated solar monitoring websites like SpaceWeather or the NOAA Space Weather Prediction Center