The August Night Sky

THE AUGUST NIGHT SKY

August is the month that we really start to notice the days getting longer and the nights shorter.

Planets

August is a poor month for seeing the planets. Only Jupiter and Mars can be seen for the whole of the month. Venus and Mercury will be visible for the first part of August. Saturn is visually too close to the Sun to be seen this month.

Mars will be visible for the first hour or so of the night. At the start of the month it sets at 19 41 and at 19 20 by month’s end. Mars starts the month in the constellation of Leo, moving into Virgo on August 29. Its magnitude is a constant 1.8 during the month.

Jupiter will be visible for the first half of the night. At the start of August it sets at 01 09 and at 23 25 by month’s end. Jupiter is in the constellation of Libra, in which it remains until December 2006. Its magnitude fades from –2.1 to –1.9 during the month.

Venus will be visible for the first part of the month in the morning twilight, low down in the Eastern sky. At the start of the month it rises at 06 12 and at 06 18 (an hour before Sunrise) by August 11. Venus starts the month in the constellation of Gemini, moving into Cancer on August 12 and finally into Leo on August 28. Its brilliant magnitude is a constant –3.9. Venus will reappear in the evening sky in late December.

Mercury will be visible in the Eastern morning sky for the first half of the month. At the start of the month it rise at 06 20, by August 10, an hour before Sunrise, at 06 19 and by August 28 it rises at the same time as the Sun, at 06 52. It starts the month in the constellation of Gemini, moving into Cancer on August 10 and finally into Leo on August 22. It starts the month at magnitude 1.3, rapidly increasing to –0.3 by August 10 and to –1.8 by the end of the month.

Saturn is visually too close to the Sun to be seen. Saturn is in the constellation of Cancer, in which it remains until September 2006.

All times are for Wellington unless otherwise stated. Other centres may vary by a few minutes.

Phases of the Moon

First Quarter – August 2 at 20:46.
Full Moon – August 9 at 22:54.
Last Quarter – August 16 at 13:51.
New Moon – August 24 at 07:10.

Occultation of Spica by the Moon on August 28

For the Southern half of the country, the bright star Spica will be occulted by the Moon on the evening of August 28. The Northern limit of the occultation is to the South of Nelson and Masterton and to the North of Wellington.

The following table gives the time of the disappearance (D) and the time of the reappearance (R), in New Zealand Standard Time (NZST). These times are given to the nearest minute. The Moon is between New Moon and First Quarter, which will make the event easier to see.

Data is also given for the positions of the grazing occultation. A grazing occultation is when the star’s path is tangential to the Moon’s surface edge. Observation by a number of distantly spaced observers can determine the topography of the edge of the Moon, by accurately timing the disappearances and reappearances of the star as it is obscured by the hills and mountains on the Lunar edge. For more information regarding grazing observations of this event go to http://occsec.wellington.net.nz/aboutus.htm .

Location / Disappear (D) h m / Reappear (R) h m / Grazing occultation
Masterton / / / 21 25 – Closest grazing occultation occurs ~10km to the SSE (Azimuth = 169°) of Masterton.
Wellington / 21 21 / 21 27 / 21 25 – Closest grazing occultation occurs ~12km to the NNW (Azimuth = 349°) of Wellington.
Nelson / / / 21 24 – Closest grazing occultation occurs ~14km to the SSE (Azimuth = 170°) of Nelson.
Westport / 21 20 / 21 27 /
Kaikoura / 21 13 / 21 34 /
Greymouth / 21 13 / 21 32 /
Hokitika / 21 12 / 21 33 /
Christchurch / 21 07 / 21 37 /
Timaru / 21 04 / 21 38 /
Queenstown / 21 02 / 21 38 /
Dunedin / 20 59 / 21 41 /
Invercargill / 20 57 / 21 40 /

Diary of Astronomical Phenomena

Aug 3 / Jupiter 5degreesN of Moon at 00 00.
7 / Mercury at greatest Westerly elongation from the Sun (19degrees) at 13 00.
8 / Saturn in conjunction (on the far side of the Sun) at 00 00.
9 / Full Moon at 22 54.
11 / Moon at perigee (closest to the Earth) at 06:00. (Distance = 0.0024048 AU = 359,750 km).
24 / New Moon at 07 10.
26 / Moon at apogee (furthest from the Earth) at 13:00 (Distance = 0.0027157 AU = 406,260 km).
28 / Occultation of Spica by the Moon at ~21 00. (See elsewhere in this Newsletter).

AUGUST SKY CHART

Click to enlarge

This chart shows the sky as it appears at about 21:00 for ~August 15.

How To Use the Sky Charts
To use the sky chart hold it up to the sky so that the direction in which you are looking is at the lower edge of the map. For example, if you are looking at the western horizon then the map should be held so that the “WEST” label is at the lower edge. The altitude and direction of the stars and planets will then be correctly shown. The centre of the chart will be directly overhead.

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