When do OAFs do Astronomy Events?

Unfortunately, Astronomy has to be done when the sky is clear and when interesting things are visible. We can predict when interesting things are visible, but the weather is always a surprise. So it’s pretty much impossible to give reliable schedules very far in advance.

For Chapters Sidewalk Astronomy events, we try to gather around a 1st-quarter moon or some interesting event like an eclipse, we watch the local Cleak Sky Chart carefully, and use the OAFs group to decide, at the last moment, whether we’re going or not.

For more formal events, such as star parties at the Carp Library, we schedule tentative dates around the phase of the moon (moonless nights are better) and, again, make “go/no-go” calls at the last moment on our group.

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Astronomy events are also scheduled around the phase of the moon.

  • For sidewalk astronomy, we like a moon around first quarter. This makes the moon visible, with interesting shadows, in early- and mid- evening when people are around. Newcomers to the eyepiece love to look at the moon.
  • We have also discovered that sidewalk astronomy works well during a full moon. This isn’t supposed to be the case — Astronomers typically hate the full moon (because it is so bright that it masks other objects, and because the full moon itself is less interesting to look at than a partial moon, because of the lack of shadows). But we’ve found that our visitors at sidewalk sessions enjoy looking at the full moon through a low-power telescope, and we occasionally hold “full moon sidewalk sessions” too.
  • For deep space star parties, the moon is not invited — it is too bright and it washes out dimmer objects. So we prefer nights of a new moon, or at least well past first quarter so moonrise is late.

Bright Planets

For deep space star parties (such as events at the Carp Library), only the phase of the moon matters. For  sidewalk astronomy at Chapters, we also depend on the location of the bright planets.

The light pollution in the Chapters parking lot is so bad that it is impossible to see anything except the moon and the bright planets (Jupiter, Saturn, Venus, and Mars), so we prefer holding Sidewalk sessions when there is at least one bright planet, plus the moon, visible. In the present years, this means late winter to late autumn are good times (since either Saturn or Jupiter are visible), but in late autumn and early winter, we have fewer sessions, since there are no good planets to show.


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