The Moon, Jupiter, and Spica – Together Again


   Wednesday February 15th the 18-day old waning gibbous Moon will be within a few degrees from the planet Jupiter and the blue-white star Spica in Virgo the Harvest Maiden as they rise in the east a few hours before sunrise local time.
   All three will fit within the field of view of a pair of 7×50 binoculars as this graphic shows.

   
   
   
   
   
   
   
   
   
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

February Moon at Ascending Node, a Penumbral Lunar Eclipse, and a Comet!

11feb-ascending-node   Saturday February 11th the full Moon will be crossing the plane of the ecliptic moving north relative to the ecliptic. This is known as the ascending node, one of two intersections the Moon’s orbital path has with the ecliptic. The ecliptic is actually the Earth’s orbit and the Moon’s orbit is inclined about 6o from the ecliptic, so there are two node intersections, the ascending and descending nodes.
   When a node crossing happens near the time of a full or new Moon there is a chance for an eclipse. The closer the two times are to each other the more centered the Moon will be with respect to the Sun for a total eclipse, or more centered such that the Moon passes through the inner and darker umbral shadow.
   That is the situation for this weekend with full Moon at 0:33 UT Saturday January 11th (6:30 pm CST Friday January 10th), and the node crossing at 19:50 UT (1:50 pm CST) Saturday. This time, due to the nearly 20 hour difference the Moon’s orbital path will take it across the Earth’s fainter outer, the penumbra. A penumbral lunar eclipse is not that easily noticeable because the bright reflected light from the Moon is not dimmed that much as the Moon passes through the penumbra.

   Click here to go to the Hermit Eclipse web site for more information about this eclipse.

   Adding to the viewing there is a good chance Comet 45P/Honda-Mrkos-Pajdusakova, aka the “Green Comet”, will be bright enough to be seen with binoculars over the next several evenings. On the 11th the comet will be at its closest to the Earth and may be brighter than 4th magnitude. Unfortunately the Moon’s reflected light will brighten the sky making it that much more challenging to see the comet. Click here to read an article about the comet at the EarthSky web site.

   Does our Moon actually go around the Earth as many graphics show? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

*Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Jupiter Goes Retro

   The giant outer planet Jupiter slows down and reverses its orbital motion on Monday February 6th as it begins its more or less annual retrograde motion. Retrograde motion is an apparent motion that occurs for an outer planet (past Earth’s orbit) when the faster moving Earth catches up with and then passes by the outer planet. During this retrograde motion Jupiter will move westward starting near the blue-white star Spica in Virgo the Harvest Maiden.

   Jupiter currently rises about around midnight local time and is very visible above the southwestern horizon sunrise.

   
   
   
   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

February Perigee Moon

6feb-perigee_moon   The Moon reaches perigee, (minimum distance from Earth), this month on Monday February 6th. At that time the Moon will more or less be at a distance of 28.91 Earth diameters (368,816 km or 229,172 miles) from the Earth.
   Does our Moon actually go around the Earth as this graphic shows? From our perspective on the Earth the Moon appears to circle around the Earth. However, in reality, the Moon orbits the Sun together with the Earth*

   On the day of the perigee Moon 13-day old nearly full Moon rises just before sunset local time and is located near the feet of the Gemini Twins.
   These two animated graphics show the sky as viewed from Quito Ecuador at 0o latitude, and my home latitude of approximately 40o North. They show the sky at one day intervals starting with February 1st and ending with February 5th.


   
   
   *Click here to read my 2006 Scope on the Sky column “The Real Shape of the Moon’s Orbit”. (PDF)

   Read this very informative article about the Earth-Moon system and their orbital motions, written by Joe Hanson. “Do We Orbit the Moon?”

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to go to bobs-spaces.

Moon Cruises Past Planets and Stars

feb5-bino
   Over the next several evenings the Moon, as it orbits toward the east and waxes from crescent to first quarter phase will pass by several planets, dwarf planets, and star clusters. On the evening of February 5th the Moon will be close to the reddish star Aldebaran, the ‘eye’ in the face of the angry bull, Taurus. This should make for a nice view with binoculars or low power eyepiece when the Moon will sort of overlay the stars of the open star cluster the Hyades.

   These two animated graphics show the sky as viewed from Quito Ecuador at 0o latitude, and my home latitude of approximately 40o North. They show the sky at one day intervals starting with February 1st and ending with February 5th.


   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.

Imbolog 2017

   Watch That WoodChuck!
groundhog newspaper   On February 2, we watch for the groundhog to emerge for reasons that originate from ancient Celtic tradition. Groundhog Day was known as lmbolog, or sheep’s milk, a time for nurturing young sheep and planting spring crops. The belief arose that if lmbolog were to be sunny and clear, then winter’s effects would endure, foreshadowing a long winter. How­ever, if skies were overcast, then the warmer days of spring would arrive early. To farmers then and today, an early spring means early spring plant­ing and a subsequent early harvest. Often fires were lit to commemorate the event as fires were a sign of warmth and light, both of which increased as days lengthened.
not a meteorologist   German immigrant farmers are credited with bringing Groundhog Day with them to the United States as they settled in Pennsylvania. To them, February 2 was called Candlemas Day, because of the practice of lighting candles on this day in celebration of early planting. The Germans believed that the badger was able to predict the weather on the basis of whether or not its shadow appeared. If the badger, or groundhog, saw its shadow on Candlemas, it would be scared and return to its burrow for another six weeks to sleep through the long winter. However, if the skies were cloudy then no shadows would appear, and an early and warm spring would be expected. The importance of this day to German immigrants, and its impact on their farming gave rise to the couplet:
         A farmer would rather see his wife upon a bier,
         than that Candlemas Day should be sunny and clear.

puxs-phil-lied   Year after year, since 1898, crowds have gathered in Punxsutawney, Pennsylvania, on February 2 to wait for a certain groundhog to emerge from its burrow. Today the belief in this as a predictor of weather is not nearly as consequential as it appears despite all the hoopla created by the news media. Yet, there is some scientific rationale to this ritual, albeit not in the accuracy of the forecast. When the skies are clear, temperatures tend to be cold as the ground radiates heat absorbed during the day back into the atmosphere; and when skies are over­cast temperatures tend to moderate as clouds trap heat nearer the ground.
Midpoints
Groundhog-Standing2   To other cultures in the Northern Hemisphere Candlemas Day was celebrated as the midpoint, or cross­ quarter day, between the winter solstice and the spring equinox. Cross-quarter days occur midway between the astronomical events that mark the beginning of each of the four seasons, the solstices and the equinoxes. The second cross-quarter day of the year, as it is calculated mathematically, occurs on May 6, although it is often associated with May Day, on May 1. The third cross­ quarter day of the year is August 7, the only one of the four without a significant event associated with it. Mid-autumn, the fourth cross-quarter day, occurs on the last day of October, Hallowmas Eve, or as we now know it, Halloween.
   Interestingly this system of equinox, solstice, and cross-quarter days has led to some confusion as to when the seasonal midpoints and endpoints occur. For example, June 21-22 is the official date for the start of summer in the Northern Hemisphere, but it is sometimes referred to as midsummer’s day. This would suggest that summer actually begins on May Day and ends in early August. In a similar manner, December 21, the start of winter for the Northern Hemisphere, is some­times referred to as midwinter’s day. This would imply winter actually begins at the end of October, and concludes (assuming no shadow is seen) on Groundhog Day.
groundhog   So will we have a long winter, or will it be short, and our spring be an early spring? No one can predict this, at least not based on seeing one’s shadow. However, come this February 2, rest assured that crowds will once again gather to watch Punxsutawney Phil emerge from his hole.
   Adapted from “Watch that Woodchuck” Scope on the Skies. Science Scope Magazine. February 1993.

   
   
   

Click here to go to the Qué tal in the Current Skies web site for monthly observing information, or here to return to bobs-spaces.