Venus and Jupiter conjoin

Venus in close conjunction with Jupiter. June 30, 2015.

Conjoin? Well, not exactly. But I don’t recall ever seeing the planets closer together in the sky than they were the night of June 30, 2015. They were both near the center of my FOV in my favorite macro lens:

Venus in close conjunction with Jupiter, June 30, 2015.

Venus in close conjunction with Jupiter. Put your cursor over the image (or click here) to see the planets’ respective distances from Earth on June 30, 2015.

Truth be told, I’d forgotten all about this conjunction of Venus and Jupiter until my father-in-law reminded me. I went out in the backyard and shot this handheld with a lens designed for close-up work. (An astronomical conjunction is not the same thing as an eclipse or occultation, where the nearer object covers up the closer; technically they just have to have the same position on one of the two celestial coordinate axes, right ascension or declination.)

The normal shooting distance to subject with this lens is about 30 centimeters. I wasn’t able to get my camera that close to Venus or Jupiter last night. (Guess I’m just lazy.) Closest approach of Venus is 38 million kilometers, and last night it was 77 million kilometers away according to my planetarium software. Jupiter never gets any closer to Earth than 365 million kilometers, and was over 900 million kilometers distant last night.

Here’s the full field of view from the photo above, without the processing to darken the background:

Venus and Jupiter close conjunction. June 30, 2015.

Venus and Jupiter close conjunction. June 30, 2015. You can mouse over the image to see the labels or click here to see a larger version.

Will try again tonight if I can scrounge up a tripod. Then I can lower the ISO and try for longer exposures.

September equinox today, 10:29 p.m. EDT

Today, at 10:29 p.m. Eastern “daylight” time, Earth’s equatorial plane intersects the center of the Sun’s disk.

Sunrise and sunset occur due east and due west, respectively, from all points on Earth’s surface.


Equinox, man!

Days and nights will continue to get shorter in the northern hemisphere, as they’ve been doing since the June solstice, culminating in the shortest day of the year (and longest night) at the December solstice.

Enjoy the equilibrium today!

Closest perigee for the moon this year

Moon, two days before full. August 29, 2012, 10 p.m. EDT.

Isn’t that a whole lot easier to say than “Supermoon”? But seriously, if you want to know what’s happening with this Sunday morning’s full moon, the best article I’ve seen in a while is over at Sky and Telescope’s website.

The moon will appear about 7% larger than the average full moon, because it’s going to be—get this—7% closer to us. 357 061 km, instead of the “average” 384 402 km.

It will appear more than 7% brighter, though, because brightness varies with the square of the distance. So, (384,4022 − 357,0612) / 384,4022 × 100 = 13% brighter.

If the average lunar brightness at full moon is −12.74 magnitudes, then this Sunday’s moon should be about −12.9.

That’s not a whole lot to write home about.

If you want to do the math, go here.

Another point to consider is that it’s the start of summer, so we’re near aphelion, when the earth is as far from the sun as it can get (the actual date of aphelion this year is July 5). That means that the light available for this June’s perigee full moon to reflect back to Earth is slightly reduced from what it could be.

On the other hand, when a supermoon (full moon at perigee) and perihelion (Earth at closest point to Sun) coincide, that’s going to be one bright full moon! (Sort of. Actually, even a 30% difference in brightness is actually not all that noticeable to most people. Our eyes scale so quickly that such a relative difference is nearly imperceptible.) If you’re curious, the next time these three events (full moon, perigee, perihelion) coincide will be January 1, 2018. That year the closest perigee full moon will occur on January 1, and Earth’s perihelion occurs only two days later, on January 3, at 1 a.m.! So mark your calendar!

In the meantime, I’ll stay up late Saturday night with my camera, hoping for clear-ish skies to restart my full moon project, which got waylaid last October.

Here’s where it left off:

June solstice 2013

Tonight at 1:04 a.m. EDT, 10:04 p.m. PDT, the earth’s orbit will carry it to that point in space where the sun’s apparent path will once again stand still momentarily before it reverses course and begins to head back south. What? How can the sun stand still? Well, it won’t, really, but the origin of the word solstice is the Latin word for “sun,” sol, and “to stand still,” sistere. And that’s what the sun appears to do at this time of year: it rises and sets in almost exactly the same spot, rather than progressing relatively smoothly from south to north as it had been doing earlier this month.

From today on, the sun will start to rise a bit later every day, and set a bit earlier. So of course, this (and the couple of days before and after it, for all practical intents and purposes) is the shortest night of the year.

So, calendrically and astronomically speaking, spring is over, and summer is here. Climatologically speaking, here in south Florida, summer has held sway since early May this year, with the early return of the rains. The heat, though, waited until about last week to really ratchet up to summerlike intensity—just in time for basketball’s Miami Heat to attempt to finish their championship run.

By the way, because the earth’s rotation is slowing down (albeit extremely gradually), the length of both day and night is almost imperceptibly increasing. 400 million years ago, days were only about 21 hours long. In another 400 million years, they should be around 27 hours long. What will you do with all that extra time?

The moon, by the way, will be about 90% full, so we won’t get a gorgeous shot like this one from APOD:

Moonrise over the Parthenon. Image by Anthony Ayiomamitis, featured on NASA’s Astronomy Picture of the Day back on June 20, 2008.

Dark(er) skies DIY

Front view after the retr

The problem: 6 peeling, light-polluting fixtures grace the exterior of the secretary of the Palm Beach County chapter of the International Dark-Sky Association, a nonprofit organization dedicated to the reduction of light pollution and skyglow.

The solution: a trip to the local Lowe’s home center and a little “sweat equity” as they say on those TV shows.

Read on to see how it happened!

I’ve lived in Florida for over a dozen years now, and have enjoyed its abundant opportunities to get out into nature day or night. During the day, I enjoy birding any of the many natural areas in Palm Beach County (most, if not all, administered cooperatively by the local municipality and Palm Beach County’s department of Environmental Resources Management). At night, I like to turn my telescopes to the stars and planets to take advantage of the warm, humid climate, which can provide good views of celestial objects.

I’ve known for years, though, that the stars are better out in the country than they are in the city. Those “billions and billions” of stars that we all know about are reduced to “dozens and dozens” in most urban areas. But get out into the desert, away from the light-polluted city nights, and you will be astonished at just how many stars there really are up there. On any given night, a good dark-sky site can show you upwards of 2,000 stars visible to the naked eye. Not quite billions and billions, but surely an improvement on the dozens visible from my backyard. (The theoretical number of naked-eye stars is around 6,000, but of those, half are on the wrong side of the horizon to see, and about one-third of the remaining total will be obscured by your local horizon.)

All of this assumes, though, that you have access to a decent dark-sky site. And lately, that has become a rarer and rarer thing. It’s estimated that nearly 75% of children born today will never see the Milky Way, because of the light pollution in their urban night sky:

Earth at night. Image from NASA’s Earth Observatory.

The view here in south Florida is just as “beautiful,” but that beauty is visible only from an astronaut’s perspective:

From our terrestrial viewpoint, it looks more like this scene from our local observatory at FAU:

Last year, a few people here in Palm Beach County decided to try to do something about this problem. We founded a local Palm Beach County chapter of the International Dark-Sky Association (Find us on Facebook; visit our website), of which I am the secretary. So I decided to do what “they” have been saying for years: think global, act local. I took a quick inventory of the light-polluting outdoor fixtures at my house. And oh my goodness! I had six of them!

1. This light was our front “porch” light; note how it shines up and sideways at least as efficiently as it illuminates the ground.

Front door light sending light sideways, up, and (somewhat) down.

Front door light sending light sideways, up, and (somewhat) down.

2 and 3. The other two lights in the front were twins to this one, only larger and with an array of special bulbs. The bulbs were burned out when we moved in and I never replaced them, knowing that I would only be replacing the fixture as soon as I could. Here is what they looked like during the day (no night-time view for these, as they never functioned):

Old glare bombs, daytime view.

Old glare bombs, daytime view.

You can see that these fixtures needed replacing not just because they would have been abysmal light polluters if switched on after dark, but for their daytime looks as well. While they might have been handsome when new, the harsh sun here has baked the finish right off them and made them rather dilapidated.

The glare bombs in front. At least the top of the fixture is metal, so the light can only go diagonally upward!

One of the glare bombs in front. At least the top of the fixture is metal, so the light can only go diagonally upward!

4, 5, and 6. We had a similar situation in the back yard: two twinned light-polluting fixtures by the French doors and a “dock light” by the garage entry, all with peeling finish.

Here in the after-dark shots you can see the “decorative” light in the foreground and the “functional” light by the garage entry door in the background throwing light in all directions, up, down, and sideways:

Glare bombs in the backyard, too!

Glare bombs in the backyard, too!


A typical "dock" light, distributing the light 180 degrees.

A typical “dock” light, distributing the light 180 degrees.

All of these needed to be replaced. So, since I had a job of work to do, and I wanted to keep the budget under control, I decided to see if I could do it myself. I’ve changed light fixtures before; how hard can this be? Short answer: not too hard. I went to my local Lowe’s, where they had a display like this (this one is from Boynton Beach, but the displays are in every Lowe’s):

IDA-approved fixtures and informational display at Lowe's 1111, Boynton Beach, FL

IDA-approved fixtures and informational display at Lowe’s 1111, Boynton Beach, FL

I purchased two different types of fixtures, in two sizes each: two medium and one small “Ellicott” model for the back yard, and two medium and one small of the dressier  “Dovray” models for the front yard. While all of these fixtures are full “cutoff” models, they are not fully focused, so while no light goes up, there is a bit of horizontal light that could be better directed downward through the use of internal baffles or reflectors. But those additional elements raise the cost of each fixture substantially, and this upgrade was already nearly $200. (Yes, that’s right: not even $200 for 6 brand new full cutoff light fixtures. This is not an IDA discount; anyone can go pick these things up for that amount.)

Here they are:

The "functional" Ellicott fixture, only $39 at Lowe's.

The “functional” Ellicott fixture, only $39 at Lowe’s.

The smaller Dovray fixture for the front entry door. Only $15 at Lowe's!

The smaller Dovray fixture for the front entry door. Only $15 at Lowe’s!

It took about half an hour to remove each old fixture, strip the wires down to new copper, hook up the new fixture, mount, seal, and repaint the wall. One or two fixtures took a bit more effort (the original installation hadn’t been sealed on one of them, and water had been coming in for over a decade, so I had difficulty unscrewing the old mounting hardware; I actually had to pay an electrician $50 to come out and help me), but by and large it was a simple, repetitive exercise and I’m more than pleased with the results.

In fact, even the problem posed by the rusted fixture had a beneficial side-effect: I was able to discover the source of that persistent water leak downstairs! Here it is; note the rust indicating prolonged exposure to water through the unsealed and poorly mounted fixture:

Rusted mount from the old, unsealed installation.

Rusted mount from the old, unsealed installation.

After the project, I had brand new non-light-polluting fixtures that are attractive day and night. Here’s the front, daylight view (apologies for the somewhat Cubist perspective) of the new fixtures:


Daylight view of the new fixtures in front

And here’s the same scene at night.

Front view after the installation of full cutoff fixtures.

Front view after the installation of full cutoff fixtures.

And here’s the view in the backyard, with two of the three new fixtures visible:

Backyard view after the retrofit.

Backyard view after the retrofit.

While the light still “leaks out” a bit horizontally, the uplight has been completely eliminated, which was the goal of the project. Not bad for a few hours’ work and a project that, without the shoddy workmanship of the original installation (which has nothing to do with the light pollution abatement), would have come in under $200!

It may not solve the global problem, but it sure helps the local area.

October 2012 full moon

October 28. 2012 Full moon

The Hunter’s moon rises nearly or completely full over three successive nights at nearly the same time each night. On Eastern Daylight Time this year, the nights of the 27th, 28th, and 29th, at 5:21, 5:57, and 6:35, respectively. Full moon is today at 3:50 p.m. EDT, but this shot was taken last night right around 10 p.m.

It was relatively far away (402 000 km), and the libration was a little over 4 degrees both east (eastern limb tilted toward Earth) and south (southern limb tilted toward Earth). With the eastern tilt, you can just barely make out the margin of Mare Marginis and Mare Smythii on the right edge (Smythii on the equator, Marginis just north of that), and with the southern tilt, if you follow the “7:30” rays from the bright rayed crater Tycho in the southern hemisphere, you should be able to see—if I’ve worked out the confusing selenography correctly—the dark floors of the large craters Schickard and Schiller. Clavius looks as large as a lunar sea, with the prominent crater Porter in its northern rim:

Southern lunar highlands with prominent features labeled. The only one I’m sure of is Tycho.

I’m having a bit of a problem with the labeling, though. Tycho is obvious. I’m fairly sure I’ve labeled Schickard and Schiller correctly. But if Clavius is that giant area near the south pole that looks almost as big as a lunar sea, something’s wrong. With the southern limb tilted four degrees toward us, I’m surprised to see Clavius looking like it’s on the southern limb. (Then again, four degrees isn’t a huge tilt; when I simulate the view by looking at my awesome new moon globe, it’s hard to make out Clavius way down there on the bottom.)

I’ll have to try again tonight, perhaps with higher magnification.

Here’s the full moon gallery to date; I’ve only missed a couple since December 2009!

September 2012 full moon: the birthday edition!

September 29, 2012 Full moon

The 2012 harvest moon occurs tonight at 11:19 p.m. EDT. Only 395,493 km from Earth tonight. Libration, as you can see, is quite southern (see how far the bright crater Tycho is from the bottom edge?), and a bit of the eastern limb is more visible as well (if you know your selenography, you can make out the bright pixels representing Gibbs almost dead center on the right-hand limb).

As you can see, I’m still working on the focus problems; the low clouds that make the slight haze around the moon are out of my control, but I should at least be able to focus the darn image.

Happy Birthday to me. Time to order myself the Sky & Tel moon globe!

Happy equinox!

Late this morning, Earth’s orbit around the sun brought it to the equinoctial point. Today the sun rises due east and sets due west. But despite the etymological indication of “equal night,” day length and night length are only approximately equal today. (For more on this, see my post from 2009.) How closely equal they are depends on your latitude. For my latitude (around 26°N), the day is about eight minutes longer than the night today, but by the 27th sunrise and sunset will be exactly 12 hours apart.

In Los Angeles, about 8 degrees farther north, today is 4 minutes shorter than it is here: 12 hours and 3 minutes. And, due to a quirk in timing, there is no calendar date with “exactly” equal length day and night. On September 25th, the day is 12 hours and 1 minute long, and on the 26th, it’s 11 hours and 59 minutes.

Go figure!

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