A Virtual Tour of Mauna Kea

Here is a collection of photographs I took between 1997 and 1999 while working as a Telescope Systems Specialist at the Joint Astronomy Centre, Hilo. For those of you not fortunate enough to have a chance to go there, let me introduce you to some of the sights and telescopes of Mauna Kea.

The first view that most visitors get of Mauna Kea is on the inter-island flight from Honolulu. The Big Island is composed of a series of dormant and active volcanoes, dominated by Mauna Kea ("White Mountain") and Mauna Loa ("Young Mountain"). Mauna Kea, at 13796' is the taller of the two, but Mauna Loa has the greater mass.

Just before the plane sinks into the clouds that (usually) surround Hilo, you get a good view of the telescopes; the easiest ones to spot are twin domes of Keck I and II, the silver domes of Gemini and Subaru, and probably CFHT as well. Hilo has the dubious distinction of being "America's Rainiest City", on account of the easterly trade winds which try to force air over the saddle between Mauna Kea and Mauna Loa, causing on average 129" of rain a year. However, much of this falls at night, and the rain is often highly localised. You just get used to it.

Hilo is fast becoming a rival to Tucson as "Telescope City". Adjacent to the campus of the University of Hawaii at Hilo are the headquarters for the Japanese Subaru telescope (the white concrete "bunker" shown in the middle), the Joint Astronomy Centre (red building to the left), the multi-national Gemini telescope (new building to the left of JAC), Caltech Submillimetre Observatory, and (in due course) part of the University of Hawaii's Institute for Astronomy.

Now to the summit itself. Up on the summit ridge are most of the older telescopes on Mauna Kea. Shown here, L to R, is UKIRT, the University of Hawaii's 88" telescope, the enormous dome of the Gemini North 8-m telescope, and the Canada-France-Hawaii 3.6-m Telescope. Between UKIRT and the 88" can be seen Haleakala volcano on the island of Maui. For an aerial view of the Mauna Kea telescopes, see Richard Wainscoat's page.

This is "my" telescope, the United Kingdom Infra-Red Telescope (UKIRT). Until the arrival of the Gemini mirror, UKIRT had the largest single mirror on Mauna Kea, and is still the world's largest telescope devoted solely to infrared astronomy. This means that there is no eye-piece on the telescope; we use a TV camera and a CCD to locate stars "visually", and then offset from these to our infrared targets, which are often "invisible". UKIRT was constructed in the late 1970s on a tight budget, which necessitated some design compromises; the orange yoke, in which the blue telescope tube sits, and which swivels to track the motion of the stars, also prevents the telescope from being pointed any further north than +60^o. Nevertheless, it can reach as far south as -42^o.

These are my parents, David and Lorna, standing in front of UKIRT's primary mirror. I owe them a great deal of gratitude for allowing their son to follow his dreams of becoming an astronomer, no matter where it took me, and how crazy it seemed when I was growing up in New Zealand.

This is a picture of UKIRT in action. If you look closely, you can see moonlight on the top-end ring of the telescope and on the orange yoke mount, as well as a couple of star trails through the dome shutter, indicating this was a time exposure of about 15 minutes.

Our sister telescope, also operated by the Joint Astronomy Centre, is the James Clerk Maxwell Telescope, a 15-m antenna designed to operate at very high frequencies (wavelengths shorter than 1mm). The tall cylinder encloses and protects the telescope; the curved surface at the front is a Gore-Tex screen which prevents sunlight and wind from impinging on the antenna, but which is transparent to radio waves.

Inside, we see the highly accurate surface panels of the antenna, and the elaborate support structure that keeps the dish in perfect shape as it rotates and tilts to follow the sources. The red cylinder visible just behind the antenna houses SCUBA, the Sub-millimetre Common-User Bolometer Array, which is a pioneering camera which allows astronomers for the first time to take "pictures", rather than the old method of building up an image by scanning the telescope back and forth across the source.

The biggest optical/infrared telescopes in the world are both on Mauna Kea, and belong to the W. M. Keck Observatory, operated by the California Association for Research in Astronomy in Waimea. The majority of Keck observers don't even come to the summit to observe; instead, they work from the comparative comfort of an office in Waimea, and communicate with the telescope via high-speed fibre-optic communications. Each of the 10-m diameter mirrors are made up of 36 hexagonal segments, each 1.8m across, which are kept aligned to a very high accuracy using a system of edge-detectors and actuators. But if you don't work for Caltech, or the University of California, or if you're not a planetary astronomer, you can forget about trying to get time on either of them. Here, Bill Allen stands at one of the Nasmyth foci of Keck I, while the Telescope Operator, Joel Aycock, gets ready for another night's observing.

Just to give you a sense of scale, here I am with Bill and Rose Allen in front of the Keck's tertiary mirror. This is a flat mirror which sits just in front of the primary mirror at a 45^o angle and reflects light coming from the secondary mirror out to one of the Nasmyth foci shown above. This mirror is as big as the largest optical telescope mirror in New Zealand!

One of the newest arrivals on Mauna Kea is the first of the two Gemini 8 metre telescopes. Gemini is a multi-national partnership between the USA, the UK, Canada, Argentina, Brazil, Chile, and Australia to build two of the world's finest optical/infrared telescopes. The first is now approaching completion on Mauna Kea, and the second is well underway on Cerro Pachon in Chile. In order to assist in delivering the sharpest intrinsic image quality of any telescope on the mountain, these large "clam-shell" vents around the exterior of the dome can be opened in order to ensure that the telescope enclosure is in thermal equilibrium with the outside air.

This view of the dome interior shows how elegant the telescope structure is. Besides keeping the weight of the telescope down, this low profile helps minimise the heat output of the "warm" telescope, making it that much more sensitive to young stars and distant galaxies. The crates hanging beneath the mirror cell will support a number of different instruments, which can be rapidly switched as conditions warrant.

The other "new kid on the block" is the Subaru 8.2 m telescope of the National Astronomical Observatory of Japan. Contrast the cost of the Gemini telescopes (US$160M for two) with that of Subaru (US$400M for just one). No expense has been spared on its construction, but then the Japanese have never attempted anything this big in astronomy before. I'm still curious to know how they intend to remove snow from the flat part of the roof... (photo courtesy of Bob Potter).

Here I am standing under the mirror cell of the Subaru Telescope with Bob Potter, ex-Mauna Kea tour guide and now one of the Subaru telescope operators. The metal strips on the floor are used to guide robots as they swap instruments at the Cassegrain focus behind me. The blue coating on the telescope steelwork is, like Gemini, an attempt to minimise thermal emission from the telescope itself.

Most days, the saddle between Mauna Kea and Mauna Loa is filled with cloud as the easterly trade winds attempt to pass between them. But often before sunrise, the saddle is empty of cloud, and one gets a great view of the numerous cinder cones left over from previous eruptions of Mauna Kea. On some mornings, the glow from Pu'u O'o, the currently-active vent of Kilauea volcano can be seen, as can the steam plume where the lava enters the ocean.

This is the view from about the 11000' level of Mauna Loa, looking back across the saddle to Mauna Kea. The National Oceanic and Atmospheric Administration (NOAA) operates the Mauna Loa Observatory here as an atmospheric baseline station for the Climate Monitoring and Diagnostics Lab (CMDL). Hawaii has some of the cleanest air in the world (not counting the vog emitted by Kilauea), and some of the dust particles trapped here can be traced all the way to deserts in China.

Sunsets from Mauna Kea are just spectacular. It's no wonder that so many tourists violate their car rental agreement to drive up to the summit to watch one. I'm lucky -- I used to get paid for this. Unfortunately, most people are too busy watching the sun sink low in the west to notice the immense shadow cast by Mauna Kea itself in the east. Regardless of the shape of the mountain, the shadow is an awesome cone of darkness that climbs its way from Hilo up towards the blue horizon, and eventually merging with the Earth's own shadow in a gorgeous pink, or sometimes crimson, sky. A full moon adds to the spectacle.

Of course, the mountain's shadow is also visible at sunrise, but here projected beyond the cinder cone Poliahu, and the assorted dishes of "Millimetre Valley". The "golf ball" houses the Caltech Submillimetre Observatory, the tall white cylinder is the JCMT, and the barn-like building is the antenna maintenance facility for the Smithsonian Millimetre Array (still under construction).

Another phenomena quite often seen are these "anti-crepuscular rays", caused by clouds on the western horizon at sunset casting shadows all the way across the sky to the eastern horizon shown here. These rays are in fact parallel, but as they recede into the distance, they appear to converge (the well-known "railway tracks" illusion). The rays are called "crepuscular" in the direction of the Sun, and "anti-crepuscular" when opposite the Sun.

As the last rays of the Sun reach Mauna Kea, often after passing through large amounts of vog (a volcanic haze of sulphurous gas belched by the Kilauea volcano) or cloud on the horizon, the light changes to a warm, soothing yellow, or maybe a dusky shade of orange or pink. Here, the glow is reflected from the wall of the University of Hawaii's 88" telescope. After sunset (and before sunrise), all the colours of the rainbow can be seen on the horizon, including green and turquoise.

Every sunset is different, but what I particularly look out for is the famous "Green Flash", in which the last little bit of the sun above the horizon turns a distinct green colour for up to a few seconds. There is still some debate over the exact reason why the last bit of Sun appears green, but some combination of refraction (which means the "red sun" sets first) and scattering (which removes most of the blue light) seems to be responsible. For a more thorough overview of the green flash phenomenon, see Andrew Young's page. I have made numerous attempts to see and photograph the Green Flash, but in more than 60 nights of looking, have seen a distinct tinge of emerald green on only 2 or 3 occasions. Here is a picture of one of them.

Don't believe me? Here's a blow-up of the previous image (taken with a 200mm lens on Kodachrome 64 slide film). No fiddling of the colours has been done; this is pretty much as the slide looks. Notice how the top slice of sun has been broken up into 4 segements, one of which is green. These knots are separated from the main body of the sun by clouds and by a mirage-type effect.

And just to show that any flat horizon will do, here is my attempt to capture a green flash atop the Subaru telescope. The remarkable thing about this is that by jumping up and down, or moving from side to side, it is possible to make the Green Flash re-appear several times or last several seconds as the Sun slides down the side of the enclosure. I did not believe that a sharp edge so close (about half a mile) could yield a Green Flash, but indeed I saw it several nights in a row as the Sun set behind Subaru just a few a few seconds before setting properly.

Here's another example of how the Sun can be broken up into multiple images -- 3 of them in fact. I've always been fascinated by atmospheric effects, like Green Flashes, sun-dogs, rainbows, and haloes. There's a lot to see in the sky if you only take the time to look up every now and then.

Here's a blow-up of the previous image. The lower image of the sun is seen through large amounts of haze, making it deep red in colour, while the notch at the top of the clouds provides the small blob at the top.

Here's another interesting phenomena you see occasionally - a "sundog" as seen over the Keck telescopes near sunset. Sundogs (also known as parhelia) are an effect due to refraction of sunlight by ice crystals high up in the Earth's atmosphere. They may be seen in pairs, 22 degrees either side of the Sun in a line parallel to the horizon (or on only one side if conditions are not right), and possibly as part of a complete halo.

A related phenomena is this "fogbow" over UKIRT. By standing with my back to the setting Sun as a very light mist blew over the summit ridge, I could see a halo almost 220 degrees around. Note the lack of colour compared with the traditional rainbow.

Few people come to Hawaii packing winter clothing, but even in July, snow is not unknown on the summit of Mauna Kea. Ice is even more of a problem; it makes the road (especially the sealed section near the top) treacherous, it can stop the dome from being opened or rotated, and it can injure people and damage vehicles when it breaks loose. So take notice of the signs!

Of course, living in Hawaii is not all work and no play. One of the great things about being there was being able to play on some magnificent golf courses, and no-one caring what your handicap is (my handicap is that I can't get the ball more than a foot off the ground). Here I am playing the "signature hole" of the Mauna Lani South course, the No. 15 par 3 which is tee, ocean, green. I have witnesses to the fact that I got on the green in one (just don't ask me what my score for the round was...)

Something else Hawaii is famous for are its volcanoes. The Kilauea volcano has been pouring out lava almost continuously since 1983. After leaving the crater, lava travels mostly underground through a network of lava tubes before entering the ocean. As you can imagine, when fire meets water, it makes for a pretty spectacular sight! When I was there, the ocean entry point was about 4 miles from the end of the Chain of Craters Road. A 2 hour hike across rough lava would get you up close, but you wouldn't want to spend too long out there - the lava bench created by the rapidly cooled lava is highly unstable, and every now and then several hundred square feet of new land collapses into the sea, taking the odd tourist with it. While well worth the effort to see Mother Nature in action (especially after dark), the hike to the lava is not to be taken lightly - remember to take plenty of water, a torch/flashlight, sturdy shoes, and gardening gloves are a good idea in case you slip on the sharp rock.

From the summit of Mauna Kea, Hilo is only 90 minutes away by road and 14000 feet down. Fortunately, light pollution is not currently a problem, although a close watch will need to be kept in the future to ensure sensible lighting regulations. More of a problem is the nearby Pohokuloa Training Area, when the armed forces decide to light up the saddle with a parachute flare or two. The first time I saw one of these, I thought Mauna Loa was erupting. Of course, we're overdue for another eruption, so I just hope I'm up here to see it, and not down in Hilo dodging a lava flow.

Look ma, no dome! (If you'd like to know how I took this photo, click here.)

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