Night_skies_08-03

Jeff Green | Jan 24, 2008

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This month we have the chance to see all five of the bright planets and a Total Lunar Eclipse from beginning to end.

At the end of evening twilight on every clear night during the month, we are bound to notice the distinctive and very bright stars of Orion, the Great Hunter, marching westward through the southern part of the heavens. Most readers are by now familiar with the names of the luminaries outlining the body of this giant: Betelgeuse and Bellatrix marking his shoulders, Saif and Rigel marking his knees, and his belt adorned by a trio of jewels with the Arabic names: Alnilam, Alnitak, and Mintaka. In addition, a huge circle of six stars (sometimes called The Winter Sextet to balance the Summer Triangle) surround the Great Hunter: Sirius and Procyon downward and to his left, marking the presence of the hunter’s two dogs (Canis Major and Canis Minor) following on his heels, Castor and Pollux (the “Gemini-stars” or The Heavenly Twins) also on his left but well above the brilliant ‘dog-stars’, Capella – once called The Goat Star, surrounded by her flock of “kid-stars” well above Orion’s head, and then to his upper right, beyond the stars marking the shield held on his left arm, the cluster of stars called The Hyades, or the Head of the Bull, itself dominated by the reddish star called Aldebaran. Some people complete the Great Circle with the brilliant star Rigel, seen as one of Orion’s knees, making it actually ‘a circle of seven’ unless they count the Twin Stars (Castor and Pollux) as a single object. In all, the 14 stars just mentioned are among the very brightest to be found in any part of the entire sky during any season of the year. In fact, Sirius is the sky’s brightest star of all, and the other five in the Great Circle are among the “top 25". Two of Orion’s own stars are among the “top 10" in brightness. Little wonder that even experienced skywatchers never tire of this display of heavenly brilliance!

Observing all five of the naked-eye planets will be quite easy this month. Reddish Mars will be the first one seen in evening twilight – very high in the southeast above the “head of Orion” and to the left of Aldebaran, the red eye-star of Taurus, the Bull, in fact, between the two stars that mark the ‘ends of the bull’s horns’. Careful observers will easily note two things about Mars over the course of the month: firstly, its orbital motion around the sun carries it to the left until, by month’s end, it is not in Taurus but in Gemini, at the ‘feet of the Twins’, and secondly, it fades from being brighter on February 1 than any of the winter stars except Sirius to being fainter at month’s end than Rigel (See above.). In fact, at month’s end, its brightness is exactly the same as that of Saturn, the second planet to be seen in the evening sky.

Throughout the month Saturn rises in the east at about the time of sunset, moves across the sky during the night, and sets in the west at about the time of sunrise. During late evenings, it is easily seen in the east, just below the star Regulus, the brightest star in the constellation Leo the Lion. Owners of small telescopes can enjoy views of the rings of Saturn and several of its moons, but they should postpone observing until late in the evening when Saturn has risen high enough to be above the haze and atmospheric turbulence often found at lower altitudes.

This month’s true planetary highlight is for those who observe the eastern morning sky in the hour or two before sunrise. At that time, Venus, by far the brightest object in any moonless sky, is dominating the heavens with its brilliance. No, it’s not a UFO! In the eastern morning sky, the two brightest planets, Venus and Jupiter, continue the “planetary dance” they began as they approached one another in the last 10 days of January, and on the morning of February 1, they will be less than one degree apart! That is, less than the width of a fingernail held up at arm’s length! (Of course, they are not actually close to each other; Jupiter is far more distant than Venus!) As these two beacons of light waltz away from each other, their progress will be very easy to follow morning by morning. On February 2, they will be over a degree apart, and that amount increases by about a degree a day until, by month’s end, they are over 30 degrees apart! Small telescope users will be able to have both planets in a single field of view for a day or two, and will be very interested to see that, though it is much farther away from Earth, Jupiter, the King of the Planets, still appears, in their eyepiece, over 2 times larger than Venus! Careful observers will also note that, besides moving way from each other, one planet rises much earlier as the month progresses; by month’s end Jupiter, in fact, rises in the east three hours before the sun, but Venus makes its appearance only one hour before sunrise.

Finally, the planet Mercury, which was seen in the evening sky in January, will be visible in the morning sky in the latter half of the month. After February 18, look for it below Venus very low in the east, beginning about one hour before sunrise. Binoculars may assist in finding it, since morning twilight may be a problem. Be sure that no buildings are blocking your view of the eastern horizon. Don’t miss the spectacle on the morning of February 27 when Mercury is only about one degree above Venus! It is the second time this month that Venus has had a very close dancing partner!

Since it is now almost six months since the last ‘eclipse season’ and there are always at least two eclipses in each such ‘season’, we have both a solar and lunar eclipse in February. At the time of the New Moon on February 6, there will be an annular solar eclipse, but since it will be visible as such only in parts of Antarctica, it will be seen by few, if any, human beings, though probably by thousands of penguins! The lunar eclipse on February 20, a Total Lunar Eclipse, in fact, is one that will be visible in its entirety in most of North America, and, weather permitting, should be enjoyed by many millions of people, since no equipment at all is required to view such an event. The following timetable should guide your observing plans. Locally, that evening the moon rises at 5:23PM, just 18 minutes before the sun sets at 5:41. The Full Moon makes its first contact with the Earth’s penumbra, its outer partial-shadow, at 7:35PM, though it will not be detectable. The first noticeable darkening on the left limb of the moon will probably be at about 8PM. The Partial Phase of the eclipse begins when the Moon first touches the Earth’s umbra, or central shadow, at 8:43PM. The Total Phase begins when the Moon is completely within the umbra, at 10PM. Mid-Eclipse is at 10:26PM. The 51 minutes of totality end at 10:51PM. The second part of the Partial Phase lasts from then until 12:09AM. The last bit of perceptible shading on the right limb of the moon will probably be at about 12:45AM, though technically the moon will not be out of the Earth’s penumbra until 1:17AM. The bright star slightly above and to the right from the moon will be Regulus, brightest star in the constellation Leo the Lion. The bright object to the left will be the planet Saturn.

One of the most notable lunar conjunctions this month is on the night of February 15 when the moon appears to be only about a degree north of the planet Mars. If the planet is difficult to see, just block out the moonlight by holding a finger in front of it. By watching them for a couple of hours, you can actually detect the moon’s real orbital motion (around the Earth).

More information about stars, eclipses, and observing is available in the book The Beginner’s Observing Guide now on sale at Sharbot Lake Pharmacy.