CAUTION: Do not attempt to observe the events described in this post without using approved eye protection. Sunglasses are not enough. The Sun’s light is intense, even during an eclipse, and contains ultraviolet radiation. That stuff will cause permanent damage to your vision. If you are not already an astronomer who understands proper filtering hardware, contact a local astronomy club for advice. Many clubs are hosting public viewing events using safe equipment. If you want to come up with something on your own, read this good advice at Space.com.

Next Sunday, a solar eclipse will be visible from East Asia through Western North America. It starts in Asia at 20:56 UT May 20th, and ends in North America at 02:49 UT May 21st. If those times and dates are confusing, note they are given in UT (Universal Time). That’s the usual protocol for astronomical events visible from multiple time zones.

• To convert between local time (what your clock shows) and UT, see our handy GMT/local time display.
  

What you’ll see in the sky depends on your geographic location. Global eclipse maps are available online: this one’s nice. If you’re lucky enough to be near the centerline, yourself lined up with the Sun and Moon, what you’ll see will be like the animation above on the right. This is what’s known as an annular eclipse, from the Greek “annulus” which means “ring.” Note: Both animations are running at about 1250 times real speed.

At maximum eclipse, for a few minutes, a “ring of fire” will surround the Moon as the Sun lines up behind it. That annularity will last for 5 minutes 46.3 seconds at its maximum (a point near the Aleutian Islands). Anywhere else on the centerline, annularity ranges from that maximum down to zero.

If you’re outside the path of annularity (which is only about 200 miles wide) you’ll see a partial eclipse, similar to the animation above left. Just how partial it’ll be depends on your distance from the centerline. U.S. readers: check this map. The path of partiality extends as far south as northern Mexico, and as far north as Washington (state) through Kansas.

I’d like to point out a few things about my animations. First, yes, I understand that you won’t be seeing any stars during this event (other than our own Sun). But the physics behind this event is occurring out in space, so I chose stars instead of blue sky to better establish our frame of reference.

Second, eclipses are often described as “the Moon passing in front of the Sun.” In reality, it’s the Sun that catches up to the Moon and passes behind it. Of course, all motion is relative. These animations show the event as you would see it from the geocentric (Earth based) frame of reference.

Third, and maybe you’ve already noticed, the Moon in the annular eclipse animation is slightly smaller. During an annular eclipse the Moon is farther from Earth, so it appears smaller compared to the Sun. The Moon’s orbit around Earth is slightly elliptical, so it can be as close as 356,577 km, or as far as 406,628 km. This is what makes an annular eclipse possible. If the Moon were closer, it would appear larger and block the entire Sun. We’d see a total eclipse.

I traveled to New Mexico back in 1994 to photograph another annular eclipse. Clouds in the sky filtered out most of the light. I didn’t need any special filters on my camera, so I attached it directly to a spotting scope. [I still used eye protection when looking toward the Sun.] What I got is shown below. Click on the thumbnail to enlarge. As you can see, I was almost exactly on the centerline. Missed it by that much … < 1 mile. But there was no road, and it wasn’t public land.

So good luck catching this celestial event, and clear skies! I’ll be at my home in New River, AZ, photographing the partial eclipse through an Hα (hydrogen alpha) filter. These high-tech filters can capture solar flares, in addition to the silhouette of the Moon. Watch for my results here in Sky Lights 2 or 3 blogs from now.

Question: I saw this star last night that was really twinkling, like it was almost blinking on and off. I know it wasn’t an airplane, since it didn’t move. And I swear I could see all the colors of the rainbow sparkling in that twinkle. What the heck was that? Some kind of multicolored star? — RW, Cave Creek, AZ

Answer: If it wasn’t moving, and if it was fairly bright, and especially if it was low in the sky, what you saw was probably just a normal star doing its normal thing — twinkling (aka scintillation).

When light from a star enters Earth’s atmosphere, three optical effects occur. First, the light undergoes dispersion, the separation of spectral colors. As you probably know, normal “white” light is a mixture of all colors. These colors travel at identical speeds in the vacuum of space. But each color has a slightly different speed in air, which is what separates them. A similar thing happens when light passes through a prism, or a water droplet (as in a rainbow).

Second, the light changes direction. It’s another optical effect called refraction, and it’s closely related to dispersion. Violet-blue changes the most, red the least. This occurs at the instant light passes from the vacuum of space into our atmosphere, where its speed is reduced by about 0.03%.

Third, on their way to your eyes, the different colored light rays are subjected to atmospheric turbulence. This causes them to change direction many more times. Sometimes the rays hit your eyes, sometimes they miss. It’s a dynamic effect that you observe as twinkling. The graphic above exaggerates the effect. What it looks like to the eye is shown below.

This video features Sirius, the brightest star star in the sky, magnified about 200 times. Sirius was near the horizon, where twinkling is enhanced by thicker air lower in the atmosphere. This 5-second video will continue to loop automatically, and shows what is intrinsically a blue-white star flashing red, violet, and (if you watch closely) also some green and orange. Those colors are dispersion working its magic.

All stars twinkle, but the effect is most pronounced with brighter stars when they’re near the horizon. Next time you recite the classic poem Twinkle Twinkle Little Star, consider that this poem was written right around the same time the physics of dispersion was being sorted out. Jane Taylor wrote that poem in the late 18th Century.

The photo above was taken by Roger Serrato, a colleague of mine from the Desert Foothills Astronomy Club. Roger’s an expert photographer who works with both film and digital media. His image shows an elusive but beautiful phenomenon known as iridescent clouds. The effect itself is called irisation, from the Greek Iris, goddess of the rainbow.

I say “elusive” because this is usually a very faint effect, and the ambient light and camera settings have to be just right to capture it accurately. It’s not nearly as intense as a rainbow, but can show the same spectrum of colors. However, there are some significant differences between iridescent clouds and rainbows.

Rainbows are always found opposite the Sun in the sky, but iridescent clouds are always seen near the Sun. That means they’re in a brighter part of the sky, so unless you have something to block the Sun (cloud, building, mountain) the subtle pastel colors will be washed out. For Roger’s photo, the Sun was setting behind a mountain. Conditions were ideal.

Further, rainbows are caused by refraction and reflection of sunlight. Iridescent clouds are caused by diffraction and interference, from small ice crystals or liquid water drops suspended in clouds. If you want a more detailed explanation, look here. If you don’t care to engage the science, skip to the last paragraph.

There are several things that can cause a ray of light to change directions. Reflection is the most common, and it’s what happens when light strikes a mirror or other shiny surface. Refraction is a “bending” of light rays when they pass from one transparent medium to another, as when light enters a diamond or raindrop. Diffraction is more of a “scattering” effect, which happens when light rays strike an object comparable in size to the wavelength of light (about 0.00002 inches, or a thousandth the thickness of a dime).

In the case of diffraction, the scattered light waves can interfere with each other to produce colors. This is a process where light waves overlap, and either reinforce or cancel their intensity. Different colors have different wavelengths, so you get these beautiful color patterns. That same process produces the colors you see in an oil slick floating on water.

As with Sun Dogs, if you take the time to look for them, and stand where the bright Sun is blocked by something, you can often see iridescent clouds you otherwise would have missed.

At sunrise or sunset you can see an interesting optical effect caused by light’s tendency to travel in straight lines. If you live in a mountainous area, as I do, the effect is even more pronounced. Every year near the Equinox, the Sun sets in a valley west of here. Its light illuminates New River Mesa and some of the other foothills, but is blocked from illuminating the New River Mountains (in the distance) and my locale (foreground). It’s a beautiful interplay of light and shadow.

The inset shows a similar effect, but on the Moon near a major crater named Copernicus. If you watch these mountainous areas through a telescope, you’ll see peaks on the night side slowly become illuminated during the lunar sunrise. What starts out as a tiny point of light (the very peak of a mountain) becomes a fully lit mountainside in a couple hours. You can actually see the illuminated area grow as you watch.

But there’s one big difference. On Earth, once the Sun reaches the horizon, and depending on your latitude and season, it can take anywhere from 2 minutes (at the Equator) to weeks (at the poles) for the whole Sun to become visible. For most sunrises in temperate latitudes, the average is 5-15 minutes.

On the Moon, where night and day last for 2 weeks, sunrise is a more gradual process. About the fastest it can happen is one hour. Again, that’s from when the Sun first touches the horizon until it’s fully visible. Check out the time-lapse video below to watch light & shadow on the Moon. The video compresses 4 hours of real-time into a mere 15 seconds.

http://www.youtube.com/watch?v=ZAw7_jq2HPw

By the way, the “X” shaped object you watched coming into view is known as “The Werner X,” after nearby Werner Crater. It’s really just some cliffs and mountains, but shows up as a distinct “X” at lunar sunrise.

Sunrise on the Moon was first witnessed by Galileo in 1610, not long after he invented the astronomical telescope. In his classic work, Sidereus Nuncius (Starry Messenger), he actually used the phrase “sunrise in the mountains of the Moon.” His observations established, as scientific fact, that the Moon has geology and topography much like the Earth, a matter that had been debated for centuries.

I should probably mention one other difference between sunrise (or sunset) on the Earth and Moon. Because Earth has an atmosphere, we experience periods of gradually increasing or decreasing light known as dawn and dusk. Not so on the Moon, which lacks an atmosphere to scatter and diffuse the Sun’s light. On the Moon, when the Sun rises or sets, it’s like throwing a light switch … the transition between day and night is nearly instantaneous.

I had this photo in my archives, and it was just too pretty not to use. So today I’ll be talking about “pink snow.” The photo shows the New River Mountains, about 10 miles northeast of my home, at an elevation of 5000 feet. Virtually every winter, they get a few nice dustings of snow (the white kind). This shot is from February of 2010.

The snow looks pink because the photo was taken just before sunset, and the ambient light had a distinct reddish tinge. We often see the same effect on Gavilan Peak, a mountain just east of here. The mountain is covered with the usual greenish-brown desert foliage, but note how everything has a distinct reddish hue. This photo was also taken at sunset. Click on the thumbnail to enlarge.

The basic idea is that light from the Sun normally contains all colors, so landscapes normally appear in their “true” hues. But at sunset, when the shorter wavelengths of light (violet, blue, and green) are filtered out by Earth’s atmosphere, you can get some interesting and beautiful effects. If you’re curious about why sunsets are red, click here.

Of course, you can see the same effects at sunrise (if you get up that early). But during most of the day, when the full spectrum of colors is available, you see things more or less as they really are — in true and accurate color.

This brings to mind an old philosophical conundrum closely related to Plato’s Cave. How does one know if what one sees is the truth? Modern science is quite good at explaining optical effects, but perception is a “whole ‘nuther thing.” What the human brain sees is intimately connected to the function of the eye. And what the eye sees depends on what kinds of light it absorbs and detects. If you could see infrared light (as snakes do) or ultraviolet light (as bees do), the world would look very different indeed. So when you consider all that, maybe the snow really was pink. At least for awhile. Much later that same night, I swear the snow looked black.

Question: I saw a bunch of hot air balloons in the sky last night. Then I started wondering how they steer those things. Seems like they’re pretty much at the mercy of prevailing winds, no? — PF, London, England

Answer: Hot air balloons have considerable “steering” capability, and they do it by utilizing the natural variability of wind direction at different altitudes. They can control their altitude but, unlike blimps and dirigibles, have no horizontal thrusters or propellers to control their lateral motion. Lateral motion is driven by the prevailing wind.

The photo shows how wind direction changes with altitude. Those dark streaks are contrails formed by aircraft, probably launched in California, and now ascending over Arizona. Note how the contrails are stretched left and right by winds as the aircraft climb. I’ve seen similar effects on the trails of meteors which, of course, are heading in the opposite direction.

Whatever wind direction you sense at ground level, you can usually find it blowing in other directions higher up. A hot air balloon can reach very high altitudes … the current record is 69,986 feet! Airliners typically cruise around 30-40,000 feet. Most commercial balloon rides (the kind people book just for the fun of it) fly at much lower altitudes. Practically speaking, your average passenger would need an air supply to breath above 15-20,000 feet.

To answer your question: When the pilot wants to change lateral direction, it’s simply a matter of consulting the local NWS database, finding what altitude is needed to reach the desired wind, and ascending or descending to that altitude. So that’s how they steer these things. They can almost always get to the planned landing point, and won’t even launch if the wind directions are unfavorable.

I say “almost,” because there have been some mishaps. Do a YouTube search for “hot air balloon accident” and you’ll find many examples. Here’s a particularly nasty one:  http://www.youtube.com/watch?v=ubWPPO09xlg

My wife and I tried one of those commercial rides. Cost about $150 each. Well worth it for the experience. Here in Arizona, they usually fly under 1000 feet, sometimes skimming along low enough for the passengers to spot wildlife (which is often spooked and flushed by the balloon). We also noticed two interesting physics phenomena during our ride.

First, since the balloon is moving at the exact speed of the wind, the air feels perfectly calm. A candle flame would burn vertically, and a feather would fall vertically. Because of this zero relative wind speed, the ride is very quiet. Oh sure … you hear the burner when they turn it on to reheat the air in the balloon, but except for that it’s a nearly silent ride.

Second, voices sound weird. When you speak, sound waves are normally reflected from whatever you’re standing on and add to the direct waves that reach your ears. But in a balloon, the ground is too far below and those reflected waves are missing. It’s hard to describe the difference. Why not experience it yourself? Most large cities have several companies that provide the service. In the Phoenix area there’s close to a dozen. I say go for it. You won’t regret spending the $150.

And don’t let that YouTube video scare you out of it. Commercial hot air balloons have an excellent safety record. Pilots must be certified and licensed by the FAA, and local operators are familiar with typical flight paths and terrain. The NTSB reports an average of only 20 balloon accidents per year. Considering the total number of flights per year, that’s a lot less dangerous than getting into your car.

Question: There were these two bright objects right next to the Moon last week. I’m pretty sure one of them was Venus, but couldn’t find anything in your blog archives. My grandson asked me about them. Any ideas?  — LD, Tempe, AZ

Answer: Good eyes! That brightest object near the Moon was indeed Venus. But there’s much more to this story …

A complex celestial display is now visible in the western sky shortly after sunset. It centers around planet Venus, but also features Jupiter, the Pleiades Star Cluster, and Aldebaran, a red giant star.

First thing you need to understand is that Venus orbits the Sun inside Earth’s orbit. The orbit of Venus is shown by the dotted line. The size of its orbit is 72% that of Earth’s orbit. So from our perspective, that means we’ll never see Venus more than about 48° from the Sun. That’s the point where it “rounds the horn” and starts moving back closer to the Sun (visually, not physically). Copernicus had this all figured out, using basic geometry, around 500 years ago.

Venus reached that far point, called greatest elongation, on March 27th, when it was joined by a nice thin Crescent Moon. By now it’s moved a bit farther along in its orbit, traveling counter-clockwise as do all the major planets. If you check it out with binoculars, you should be able to make out its crescent shape. You’ll easily see that feature using a telescope. Venus goes through a phase cycle, just like our Moon, and for exactly the same reason.

When Venus is on the “back side” of its orbit, we see a fully lit circular disk (just like the Full Moon). But at greatest elongation, when the Sun-Venus-Earth angle is 90°, we see it at half phase. In the weeks to come, as it moves between Earth and the Sun, it will become increasingly more crescent-like since its lit side is facing more away from us. Remember: Planets don’t give off their own light, like stars. We only see them because they reflect sunlight.

As Venus approaches nearer to Earth, it also appears larger (see insets). It was this change in phase and size that convinced Galileo, back in 1610, that Venus (and the other planets) must orbit the Sun. That observation supported the heliocentric (Sun-centered) theory of Copernicus, and refuted the prevailing geocentric (Earth-centered) theory.

Venus will reach greatest brightness on April 30th, when the combination of apparent size and Sun angle combine to reflect the greatest amount of light. At that time, next to the Sun and Moon, it’ll be the brightest object in the sky.

Jupiter, orbiting the Sun outside Earth’s orbit, is not so constrained. It can be anywhere in the sky relative to the Sun, but just happens to be near Venus (visually, not physically) at this time. Look for it about halfway between Venus and the western horizon. It’s the second brightest object in that general area. Through binoculars, you should be able to see 3 or 4 of its largest moons as tiny pinpoints of light lined up on either or both sides of the planet.

Above Venus, and slightly to the south, is the red giant star Aldebaran, part of the constellation Taurus (aka the “Bull”). People often overlook star colors because they’re more like pastel shades. But in comparison to Venus and Jupiter (which are whitish) the reddish color of Aldebaran should be obvious.

Completing this celestial display is the Pleiades Star Cluster, which also looks nice in binoculars. Often mistaken for the Little Dipper, which is attached to Polaris (aka the North Star), the Pleiades is also part of the constellation Taurus. It does have a Dipper-like shape though, so I can understand the confusion. I’ve only shown its 6 brightest stars, but if you look at it with binoculars you’ll see dozens more.

This just in: Here’s a great photo of Venus and the Pleiades, captured on April 1st by Arizona astronomer Tom Polakis.

This grouping of objects will persist for a couple weeks, so haul out your binoculars (or telescope) and enjoy the show. You’ll get your best view between 7:15 and 8:00 pm.

Date: Late March – Early April
Time: 7:45 pm, one hour after sunset
Place: the northern sky

Early in the history of our species, predicting the motions of objects in the sky was a matter of survival. Celestial cycles were related to seasons, tides, and the migration and growth of what we ate.

Not surprisingly, most cultures developed mythologies related to these cycles. In each culture, the stars had different names. Likewise for the constellations (shapes) the stars formed. For example, according to Navajo legend:

Revolving Male [Ursa Major] and Revolving Female [Ursa Minor], run in endless circles around North Fire [Polaris] with the woman in pursuit. Black God was assisted by First Man and First Woman in his task of building the sky. He rewarded them by giving them permanent places in the heavens.

If you watch these two constellations over time, you’ll see them moving in circular paths around Polaris, the North Star. The rotational speed is about 15°/hour. This motion is shared by all stars — it’s just more obvious for those near Polaris

By the way, “North Fire” in that legend means “star that never moves.” It was a special crystal put there by Black God to aid travelers at night. And indeed, it still aids travelers who use the sky to navigate. It tells them which direction is north, and its elevation tells them their latitude.

Fast forwarding to modern astronomy, we now know it’s Earth’s rotation that causes this apparent stellar motion. The stars don’t really move. Well … actually they do, but so slowly you’d need a powerful telescope, and lots of time, to detect it. In these modern times, Black God is resting.

The two most prominent circumpolar constellations are Cassiopeia (aka the “W”) and Ursa Major (aka the “Big Dipper”). They’re called circumpolar because they circle Polaris, and from latitudes >40° are always visible. From Arizona’s latitude of 35°, the Big Dipper dips about halfway below the horizon, and the W just skims it. This time of year, both are visible and at about the same elevation.

These two constellations are always opposite each other as they revolve around Polaris. So you can always see at least one of them unless you’re deep in the southern hemisphere. To find Polaris, just draw a mental line that splits the W, or a line that extends from the front of the Dippers bowl. Those lines will point to Polaris.

Once you find Polaris, you might be surprised to see that it’s not really that bright. Somehow, the idea that Polaris is the brightest star in the sky continues to circulate. It is the brightest star in that general location, but the distinction of brightest star goes to Sirius (on the opposite side of the sky).

I’m not sure why Cassiopeia is known as the W since, as it rotates around Polaris, it sometimes looks like an “M” or “E” or “3,”  depending on its orientation. The Dipper is far less ambiguous.

Question: I hear the Spring Equinox is sometime this month. Is it really true that you can balance on egg on its pointy end when this happens? — MJ, Eureka, CA

Answer: This is an old rumor, and it surfaces around this time every year. To be honest, I really have no idea how it got started. So the answer to your question is a most emphatic NO, not with more or less difficulty than you could balance an egg any other day of the year.

The Spring Equinox, a.k.a. the Vernal Equinox, is on March 20th this year. Some years it’s on March 21st. At this time, as well as on the Autumnal Equinox, the rotational axis of the Earth is perpendicular to the plane of its orbit around the Sun. The graphic above shows the relevant geometry. [Solstice labels are for the northern hemisphere.] Because of this unique geometry several atypical things do happen:

1. The Sun rises at 6 am exactly in the East.
2. The Sun sets at 6 pm exactly in the West.
3. There are exactly 12 hours of daylight and 12 hours of night. [Equinox means "equal night."]

Well, not exactly exactly, but close enough for our purposes here. On other days of the year, the Sun rises and sets north or south of East and West, depending on the season. Also, the number of hours of daylight will be more or less than the hours of night in 24 hour day. Say, 18 hours of daylight and 6 hours of night.

Perhaps this special Equinox geometry provoked the egg balancing rumor — that, and the fact that Easter is around this time of year. Then again, maybe it has something to do with the astrological sign of the egg.

We’ve all seen these monstrosities. They clutter our view of the landscape and distract drivers. They’re commonly called electronic billboards, but the industry term is CVEMS (continuously variable electronic message signs) or EMD (electronic message displays). They’re also bad for astronomy. Much of the light they emit goes upward into the sky, adding to the already significant problem of light pollution.

Fair warning … this is a rant, and at 800+ words, it’s longer than my usual posts. But this is a topic I’m passionate about, as it affects my hobby of astronomy. So please bear with me.

They installed a huge CVEMS about a year ago at a mall 5 miles south of my home. It’s the brightest light I can see from my yard. The image above shows my new panorama to the southwest. The insert is a telephoto view of the sign. County Planning & Development tells me it’s three times brighter than their recommended level, but unfortunately, the sign is within Phoenix city limits, and Phoenix lighting ordinances trump the County.

The reason they’re so bright is, unlike conventional billboards (which merely reflect light), a CVEMS emits its own light, much like a computer monitor or television. The display consists of clusters of red, green, and blue LEDs (light emitting diodes) that in proper combination can produce any color desired. But unlike streetlights, yard lights, or conventional billboards, there’s no way to shield these things. Click on the left thumbnail below for a closer look at this sign.

Advertisers and billboard companies love these things. Multiple customers can be accommodated on a single unit. The rotating ads grab your attention. [By federal standards: no more than one ad every 8 seconds, and no full-motion video.] And no more paying a crew to remove and glue paper. Changing an ad is no more difficult than changing a slide in a PowerPoint presentation. The whole operation is run from a computer interface.

I’ve written about CVEMS before, in my last Nov 14th post. But I felt compelled to return to this subject, since HB 2757 is now winding its way through the Arizona Senate. It’s being fast-tracked by its proponents, even though it’s opposed by professional and amateur astronomers, environmentalists, and those who simply enjoy an uncluttered view of the beautiful scenery in this great state.

HB 2757, if passed, would overturn some critical provisions in the Arizona Beautiful Highways Act of 1970, itself a spin-off of the federal Highway Beautification Act of 1965 spearheaded by Lady Bird Johnson. Specifically, HB 2757 would allow the use of variable lighting (read: rotating ads) on roads throughout the state.

Click on the right thumbnail above for a larger view of the sign seen from the side. If you note the access doors, you’ll get a feel for just how big this sign is. You can actually take an internal spiral staircase to the top to service the electronics, and the AC required to keep those electronics cool. The entire system consumes close to 10 kW of electricity … enough to run 7-8 average homes. That’s a lot of energy that could be better used elsewhere. By comparison, a conventional billboard this size might use about 1 kilowatt.

I spoke with an engineer at the company that manufactured this sign. He said it cost around $350,000. Beyond that, there are ongoing maintenance and electricity costs. The LEDs should last 5-6 years in this climate, providing they aren’t “overdriven” (run at their brightest level). As it turns out, the brightness is user-variable, and the brighter you run it, the sooner the LEDs will start failing, creating “blank pixels” like you sometimes see on other digital displays.

There’s also a sensor that detects sunlight levels, and ramps the brightness down as it gets dark. But this feature is also user-variable, and not addressed by the Phoenix lighting code. Naturally, sign owners are inclined to “turn up the volume” in an attempt to boost sales, and pass along the energy or LED lifetime costs of doing so.

Another feature that’s user-variable is, of course, the ad content. It has been suggested that the impact of these signs could be mitigated by using light text on a dark background rather than the other way around. Look at the two messages below. Both have sufficient contrast to be easily readable, but the one on the right emits far more light. The companies that make CVEMS do recommend the scheme on the left, to save energy, increase LED lifetime, and reduce light pollution. Alas, few advertisers or CVEMS owners seem to be paying attention.

So if you’re an Arizona resident, this is the time to write your state senator and express your views. If you don’t know who your senator is, go to this website: http://www.azleg.gov/alisStaticPages/HowToContactMember.asp

If you’re not an Arizona resident, hopefully this post has made you better informed about this latest scenic blight.

This Sky Lights is dedicated to Howard Israel, Phoenix area Rep for the International Dark Sky Association. Howard has stepped down from that position because of health issues. We met at a stake-holders meeting where we collaborated on developing a model lighting ordinance for use by municipalities. We became friends as well as colleagues, and he spoke twice to my astronomy club over the last two years. Thanks, Howard, for all you’ve done to help us preserve our dark night sky. Your expertise, enthusiasm, and political activism as our IDA Rep will be sorely missed.