Celestial highlights for the week of Oct. 29 – Nov. 3

Oct. 29: Mercury is at its greatest elongation from the Sun (18.6 degrees from the Sun).

Mercury is always difficult to observe, even when it is at this greatest elongation angle.

You can use the brilliant planet Venus to assist you in your efforts to find Mercury this week. On this day Mercury will be 0.6 degrees to the northeast of Venus.

Nov. 1: The Moon is full. The November full moon is called the “frosty moon,” due to the cooling weather. Of course, this year, November has TWO full moons (second full moon on Nov. 30). When the Moon is full twice in the same month, the second full moon is called a “blue moon.” The occurrence of two full moons in the same month is not common, hence the phrase, “once in a blue moon,” signifying a rare event.

Nov 2: The Moon will be 6.4 degrees to the SSE of the Pleaides star cluster.

This is a gibbous moon and will be quite bright. Try to observe this star cluster within the lunar light glow.

Are you going out on Halloween night? What will you see, besides all manner of ghosts, goblins, witches and Harry Potters?


The first celestial sight to command your attention will be the gibbous moon. This moon will be full on Nov. 1 and will actually look full on Halloween night. Those enamored of occult icons will delight in the coincidence of the holiday and nearly full moon. Stargazers, however, be less enthralled, for the lunar light glow will obscure almost all the stars within 20-30 degrees.

On Halloween night, the Moon will skim along the northern boundary of Cetus the Seamonster. Cetus is a faint constellation even in a dark sky and on Halloween it will be lost in the moon-glow.



Halloween is based on an ancient Celtic holiday. Like many holidays, Halloween has an astronomical base. Halloween is a cross-quarter day, defined as a day that is nearly equidistant between an equinox and a solstice. Halloween is between the autumnal equinox and winter solstice.

There are four of these cross-quarter days altogether. The other three are:

Groundhog Day (Feb. 2): Between the Winter Solstice and Vernal Equinox

May Day (May 1): Between the Vernal Equinox and Summer Solstice

Lammas (August 1): Between the Summer Solstice and Autumnal Equinox

For information about planetarium show times, please call 780-4249


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