Star Calendar – July 2016

Star Calendar

July 2016

Star Calendar Planets:

Moon will show only 1/7 of her fullness on the 7th of the 7th month. 7/7 is the date of the oriental star festival called Tanabata – when two lovers (stars Vega and Altair), separated by a river (the Milky Way), may be allowed to meet if the river vanishes. But that is unlikely this year since the Moon is too small (dim) to vanquish the river. However, terrestrial lights may very well do the job instead; Orihime and Hikoboshi are probably big fans of Light Pollution.

Mercury crosses behind the Sun on the 6th-7th and might just be seen at the end of the month in the evening. On the 30th, with a good view to the west, Venus should shine out by around 8:30 PM. Following her descent, Mercury should appear to her left, and Regulus might just be made out very close beneath Mercury – try binoculars. That will be the nearest planet-to-bright-star conjunction for the year.

Venus should be visible (west) in bright evening twilight after mid-month or so, but she sets by around 9:PM. Mercury will pass close by on the 16th, but the sky will likely be too bright to see him. Again, one might try binoculars.

Sun is at its highest on the 4th – in the sense of distance-from-the-ground or Aphelion. Might the Earth be deemed most independent then? Proximity of the Sun slightly exaggerates the Winter/Summer of the southern hemisphere – but tempers those seasons in the north. Ocean is preponderate in the south – and it tends to subdue the seasons by great thermal mass and circulation – while land masses respond more quickly to the solar input. At present the apsides rather subdue climate change – with a residual net warming; the last ice age is still finishing up – but as the apsides shift (over centuries), a net cooling will again glaciate the north. The effect of apsides is smallish on the earth – but is large on eccentric Mars.

Mars, still brighter than any star, now culminates (is highest, in the south) as dark falls. He shone like a flying cinder during our St. John’s bonfire.

Jupiter is brighter than Mars – but is lower and further west each day when he appears. He entertains the Moon on the 8th and 9th.

Saturn makes a huge triangle with equal-brilliance stars Arcturus and Vega (the latter is slightly brighter). Saturn will gradually be higher and more southerly at first appearance each evening as the month progresses. In August he will appear in a fashion similar (in position) to that of Mars this month.

Star Calendar Days:

  1      Sunrise/sunset in Spring Valley at 5:28/20:32 (15h4m daylight)

  4      Aphelion at noon – Sun is 3% farther than in January

          Sun, Moon, Venus and Mercury between the knees of Gemini

          Equinox on Mars, autumnal for northern part

  7      Mercury at superior conjunction – crosses behind Sun

          Moon beneath Regulus after sundown

          Tanabata – oriental star festival of Orihime (Vega) and Hikoboshi (Altair)

8-9     Moon near Jupiter in West at dusk

11      Moon between Mars and Jupiter, and beside Spica, SW in evening

14      Moon, Mars, Antares and Saturn make an oblong in South at 10:PM

16      Moon, Saturn and Mars make a line over Antares at 10:PM

19      Full Thunder or Hay Moon at 6:57PM

30      Perhaps find Mercury near dimmer Regulus as Venus sets, W around 9:PM

31      Sunrise/sunset in Spring Valley at 5:51/20:13 (14h22m daylight)

Star Calendar – July, 2015

Star Calendar

July 2015

Star Calendar Planets:

Moon is Full at both ends of this month; but most comely when a companion young crescent around the 18th.

Mercury slips behind the Sun on the 23rd. Our next chance to see Mercury may come August 16th, beside a crescent Moon.

Venus now approaches us in earnest and her disk is greatly increasing in size. At the same time she is showing us less of her disk as she wanes in phase. The visible (lighted) part of Venus covers the greatest angular area of our sky as she sets on the 9th, but she continues to brighten to a maximum on the 12th. Venus and Jupiter make the closest of three encounters on the 1st, separated by only 4/10 degree as the evening darkens. Their second (RA)* conjunction is less sensational at 6 degrees on the 31st, and the third will come on October 26th – that being a morning apparition.

Sun has appeared for half the number of days for our calendar year at noon on the 1st, but does not progress halfway round the ecliptic until the next day. The discrepancy may seem odd at first but makes sense when we consider that its progress is most rapid when nearer than average (Fall to Spring) and tardier when farther away (Spring to Fall). If the calendar year were to begin at spring equinox instead, we would be halfway through the calendar on Sept 19th, but the Sun would take another 5 days to reach halfway along the ecliptic. Put another way, the time between equinoxes are 186 ½ and 178 ¾ days respectively; between solstices 181 ¾ and 183 ½. The Sun does NOT run like clockwork!

Mars is on summer vacation.

Jupiter, encouraged by a kiss from Venus, continues his quest for Regulus. The evenings of the 17th, 18th and 19th offer especially picturesque arrangements of Crescent Moon, Crescent Venus, Jupiter and Regulus; don’t miss them.

Saturn culminates (is highest, in the south, at about 9:PM) just as it gets dark this month and shines now at the same brilliance as the brightest of our summer stars, Vega. Vega is to be seen then in the east, to the left of Saturn.

*RA, R.A. or Right Ascension refers to a sky coordinate system based on the celestial equator divided into 24 sections. It is the component of distance along the equator to the left of the vernal equinoctal point and is given in units of hours, minutes and seconds where 0h is vernal equinox point. The other component is degrees Declination, which is the distance above or below the equator (+/- 90). For example, the summer solstice point is at 6h, +23.5 degrees. Conjunctions are usually (but not always) considered to be when the RA of two objects are the same.

 Star Calendar Days:

1      Sunrise/sunset in Spring Valley at 5:27/20:33 EDT (15h6m daylight)

          Halfway through AD 2015 at lunchtime

          Venus and Jupiter in nearest of triple conjunction, .4 degrees apart

          Full Thunder Moon 10:20PM

2      Sun opposite its Jan.1st position on the ecliptic

6      Sun most distant for the year, 3% farther than in January; moves most slowly

9      Venus illuminates largest area of sky

12      Moon near Aldebaran predawn in east

          Venus brightest for this appearance, -4.7 mag.

16      Moon, Venus and Regulus within smallest circle, West at 9:PM

17-19 Moon, Venus, Jupiter and Regulus gather each evening in West

22-23 Moon passes Spica, SW after 9: each evening

23      Venus stationary to stars, begins retrograde motion

          Mercury at superior conjunction, crosses behind Sun

25      Moon approaches Saturn (from the right) SSW after 9:PM

26      Moon above Antares, Saturn to right, S – SSW after 9:PM

31      Sunrise/sunset in Spring Valley at 5:51/20:14 EDT (14h23m daylight)

          Full Hay Moon 6:43AM

          Venus and Jupiter are conjunct (same R.A.) again, 6 degrees apart