Stars and Constellations

The Square of Pegasus ( an asterism of the constellation of Andromeda, the Chained Maiden which is made up of four stars of nearly equal brightness namely: Scheat, Alpheratz, Markab and Algenib) takes center stage in the Philippine night sky after sunset, which is a sign of the arrival of the northern fall. Northeast of it lies the Andromeda Galaxy (M31), the closest large spiral galaxy to the Milky Way Galaxy as shown in Figures 1 & 1a. Under clear skies and with the aid of a star map and familiarity with the surrounding background stars, it can be seen as an elongated misty patch with the naked eye and can be easily viewed through binoculars and telescopes. The splendid W formation of stars known as the constellation of Cassiopeia, the wife of King Cepheus and the mother of Andromeda in the Greek mythology, lies to the left, while the constellation of Pisces, the Fish can be found at the lower right of of Pegasus.

The famous equilateral triangle in the sky, known as the Winter Triangle rises after midnight. The Triangle formed by the stars is composed of Betelgeuse, the super giant red star and the prominent star of the famous constellation Orion, (the Mighty Hunter), Sirius, the brightest star in the sky of the constellation Canis Major (the Big Dog), and Procyon, the brightest star of the constellation Canis Minor (the Little Dog).

Fig1Figure 1
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Fig1aFigure 1a
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Meteor Shower

The October Orionids meteor shower will be active from 17-25 October 2018. At maximum rates, the shower may reach 15 meteors per hour that may be observed at favorable sky condition, but sometimes there are lulls even during the traditional maximum peak nights of 21-22 October 2018. The Earth is passing through the stream of debris left behind by Comet Halley, the parent comet of the Orionid shower. The radiant of the shower will be observed north of Betelgeuse as shown in Figures 2 & 2a.

Fig2Figure 2
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Fig2aFigure 2a
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Planets Whereabouts
On 01 October at 6:00 PM, Venus and Jupiter, will be seen dazzling brightly at magnitude -4.80 and -1.80 and will be located at about 16 and 30 degrees high in the west southwestern horizon, respectively. Venus will lie among the background stars of the constellation Virgo, the Virgin, while Jupiter, the largest planet in the solar system, will be positioned among the stars of the constellation, Libra, the Scale.

Planets Mars and Saturn can be observed at altitudes of about 44° and 52° in the south southeastern horizon and can be found among the background stars of the constellation Capricornus, the Sea-Goat and Sagittarius, the Archer shining at magnitudes -1.30 and +0.50, respectively. The Saturn system holds more than 60 satellites or moons, of which seven (7) glow brightly enough to show through moderate-aperture telescopes. Saturn’s Titan, the largest and brightest satellite, which shines at magnitude +8.4 can be easily seen through any optical instrument. It orbits Saturn once every 16 days.

On the same date at 8:00 P.M., Neptune will be located 50 degrees above the southeastern horizon among the background stars of the constellation Aquarius, the Water-Bearer with a magnitude of +7.80. Meanwhile, its fellow gas giant, Uranus, will be seen standing at about 15° in the east northeastern horizon glowing feebly at magnitude +5.70. It will lie among the background stars of the constellation Aries, the Ram. Observing Neptune and Uranus will require a binocular or a telescope and a starmap under dark and clear sky condition.

Mercury, the nearest planet to the Sun will be out for observation during the month due to its proximity to the Sun.

Figure 3 shows how to compare apparent magnitudes of celestial bodies such as planets and stars.

Fig3Figure 3
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6  Moon at perigee (nearest distance to Earth = 366,395 km) 6:00 AM
7  Ceres in conjunction with the Sun 6:00 PM
10  Venus 13° South of Moon  6:00 PM
12  Jupiter 4° South of Moon  6:00 PM
14  Mercury 7° North of Venus 6:00 PM
17  Juno stationary 2:00 AM
18  Moon at apogee (farthest distance to Earth = 404,225 km) 3:00 AM
18  Mars 1.9° South of Moon  6:00 PM
21  Neptune 3° North of Moon  7:00 PM
24  Uranus 5° North of Moon  7:00 PM
26  Venus in inferior conjunction 10:00 PM

Chief, RDTD

25 September 2018
For more information, call:

Chief, Space Sciences and Astronomy Section (SSAS), (RDTD)
Tel/Fax Nos. 434-27-15