Astronomical Diary
Last Quarter New Moon First Quarter Full Moon
Sep 3
10:37 AM
Sep 10
2:01 AM
Sep 17
7:15 AM
Sep 25
10:52 AM
Current Condition X-ray Solar Flares

Speed: 334.7 km/sec
Density: 4.2 proton/cm3
More Data: ACE, DSCOVR

Explanation | More Data
Updated: Sep 03 at 0439 UT

***The sun is blank-- no sunspots.

Credit: Solar Dynamics Observatory(SDO)/Helioseismic
and Magnetic Imager (HMI).
Daily Sun: 02 Sep 18
6-hr max: A1 2244 UT Sep02
24-hr: A1 2244 UT Sep02

Explanation | More Data

Updated: Sep 02
at 2359 UT
Time (PST) of rise and set of some planets at 10-day interval
Rise Set Rise Set Rise Set Rise Set Rise Set
Sep 8 4:57 AM 5:28 PM 8:43 AM 8:15 PM 3:24 PM *2:34 AM 10:07 AM 9:35 PM 1:21 PM *12:38 AM
Sep 18 5:36 AM 5:51 PM 8:31 AM 7:55 PM 2:52 PM *2:05 AM 9:34 AM 9:01 PM 12:42 PM 11:55 PM
Sep 28 6:09 AM 6:08 PM 8:10 AM 7:28 PM 2:24 PM *1:40 AM 9:03 AM 8:28 PM 12:04 PM 11:17 PM

* = following day
Astronomical Events September 2018

The equinox is the only time when the solar terminator (the "edge" between night and day) is perpendicular to the equator. On an equinox, day and night are of approximately equal duration all over the planet. They are not exactly equal, however, due to the angular size of the sun and atmospheric refraction.

Autumnal equinox will occur on September 23 at 9:54 a.m. Hence, thereafter, Philippine nights will be longer as the Sun moves below the celestial equator towards the southern hemisphere.

Figures 2 & 2a represents the position of the Earth and Sun during Solstices and Equinoxes.

Figure 2
(click to view image)
Figure 2a
(click to view image)
Stars and Constellations
Stargazing during the month will give a fine display after sunset and before sunrise of celestial bodies such as stars and constellations. The famous Summer Triangle of the stars Vega, Deneb and Altair of the constellations Lyra, Aquila and Cygnus respectively, is well placed above the eastern horizon, as shown in Figures 1 & 1a. This month, the rich band of constellations and stars along the Milky Way from the constellations Cygnus, the Swan, in the north, to Sagittarius and Scorpius in the south, begin to give way to fainter constellations, many of them with watery associations such as the constellations of Capricornus, the Sea Goat, Aquarius, the Water Bearer and Pisces the Fish. The famous asterism Teapot in the sky of the constellation Sagittarius can be observed at about 40° to 45° above the south southeastern horizon as also shown in the Figures.
Figure 1
(click to view image)
Figure 1a
(click to view iamge)
Planets Whereabout
On September 1 at 1:00 AM, Mercury, the nearest planet to the Sun will be found 11° above the east-northeastern horizon and will lie among the stars of the constellation Leo, the Lion shining with a -0.8 magnitude.

At 7:00 PM of the same date, Venus and Jupiter, will be seen dazzling brightly at magnitude -4.71 and -1.90 and will be located at about 25° and 43° high in the western 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 an altitude of about 34° and 52° in the south southeastern horizon. They will be found among the background stars of the constellation Sagittarius, the Archer shining at magnitudes -2.10 and +0.30, 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.

At 11:00 P.M., Neptune will be located 62° above the southeastern horizon among the background stars of the constellation Aquarius, the Water-Bearer with a magnitude of + 7.82. Meanwhile, its fellow gas giant, Uranus, will be seen standing at about 28° in the eastern 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.

Figure 4 shows how to compare apparent magnitudes of celestial bodies such as planets and stars.
Figure 3
(click to view image)

September 2018
8 Neptune at opposition 2:00 AM
8 Moon at perigee (nearest distance to Earth = 361,354 km) 9:00 AM
13 Venus 10° S of Moon 7:00 PM
18 Saturn 2° S of Moon 11:00 PM
20 Moon at apogee (farthest distance to Earth = 404,874 km) 9:00 AM
23 Autumnal Equinox 9:54 AM