A glint of Sat-X and other gems (1)

Last week was the high point of what Space Weather.Com billed as “The Naked Eye Planet Show”—a rare alignment of Saturn, Jupiter, Mars, Venus and Mercury, over the eastern horizon. The pre-dawn apparition will be visible to the unaided eye, for most of February.

In Astronomy, this configuration is called a “syzygy”—at least, by those who can say it! If you’re stumped, don’t worry. Just say, “Satellite flare” or “satellite glint” instead. True, the meanings differ: But the relationship is close enough, to clue you in on another satellite “show,” running at the same venue.

The syzygy consists of natural satellites, arrayed on one side of the Sun, with Earth lying in between. The formation commenced on the 2nd and crystallized fully on the 6th. But it’s a command performance, of limited duration. All five objects will exit, stage west, in a few weeks.

Fortunately though, nature no longer has the only satellite show in the sky—thanks to spiraling space technology. Even as the “fab five” (to use The New York Times sobriquet) take their bows, a chorus line of nearly four thousand (active and inactive) artificial satellites is arching overhead, largely unnoticed.

But not entirely. Quite a number of amateur astronomers, instructors and satellite enthusiasts delight daily in the glistening procession. In fact, satellite watching dates back to the “Operation Moonwatch” era of the late 1950s, when a network of U.S. amateurs tracked Russia’s epochal Sputnik series.

Today, several satellite-tracking websites cater to hobbyists. One can track NigeriaSat-2 and Sat-X in real time, for instance, pinpoint NigComSat-1R over East Africa or marvel at the entrancing view of our spherical planet, as seen from the International Space Station (ISS).

Tapping into this visual trove, without a viewing aid, though, is not quite as simple as feasting on the “fab five”—something our ancestors have been doing for many millennia. The main differences are “reflectivity,” “size” and “mobility”.

Neither manmade nor natural satellites generate visible radiation. What makes them luminous, is reflected sunlight. The visibility of both, therefore, depend on factors such as orbital position, orientation in orbit and the material they’re made of.

Most artificial satellites either consist of reflective metals or have large solar panels that bounce sunlight back to Earth. The problem is, they are also small and fast-moving. The Moon is not very reflective, for example. But it is huge and moves slowly in the sky. So it is highly visible.

By contrast, spacecraft are miniscule (comparatively speaking), travel at great speed and their orientation in orbit changes rapidly. Hence the reflective parts of manmade satellites beam solar radiation into our eyes at some times, but not at others.

As a result, many (ISS being a famous exception) are visible only in short spurts called “flares” or “glints”. The brightness of satellites is rated on a magnitude scale, in the same way as stars or planets—with higher numbers assigned to dimmer objects.

Last year, for instance, a spotter in the U.S.A. reported a two-second flare of NigeriaSat-X (built by Nigerian students in the U.K.), which has a brightness of magnitude “9” (far below the naked eye cutoff point of “5.5” to “6.5”).

He filed this FPAS (Fine Position of Artificial Satellite) report with Sat-Flare, an Online tracking website:

“The event was…observed…during a planned observation of this satellite with binoculars under good sky conditions from COSPAR Station 8336. The satellite was continuously observed. The flare lasted 2 [seconds] and the magnitude changed from invisible to 9…”

To be continued.

J.K. Obatala