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!

Observe the moon this Saturday

InOMN logo-transparent

International Observe the Moon Night is this Saturday, October 12. Head on out and look at the moon, just a day past first quarter and well situated for evening viewing. Get out there and get to know our nearest celestial neighbor, our partner and protector in space. Without the moon, why, where would we be?

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 […]

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 […]

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 […]

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 […]

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 […]

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 […]

Full moon in August

August 30. 2012 Full moon

The second full moon in August (well, about 12 hours before full). I found my digiscope camera!

Despite what the Clear Sky Clock for Boca Raton says, this evening had nothing but high clouds and haze overhead, so while the naked eye views through the eyepiece were steady and beautiful, the camera view was a bit more obscured. Oh, well.

August’s moons: blue or not?

This year and next year, the month of August will bring you the two different definitions of the term blue moon. As you know, every 2.7 years the twelve months of the calendar feature thirteen full moons. There are only twelve full moon names, though, so when a “year” has thirteen moons, you have to decide how to name that “extra” moon. (I’ll explain why I put the word year in quotes later.)

As a culture, we’ve collectively decided that such extra moons shall be called blue:

Whoops! Wrong kind. Here’s the kind I’m actually talking about: