Similar to last year, this July will also trigger another wave of astronomical enthusiasm due to the occurrence of a total solar eclipse. Unfortunately, this eclipse cannot be observed from within China, and the vast majority of the totality path covers the ocean. Nevertheless, many astronomical enthusiasts from around the world will still travel to observe it. Additionally, although there are no major meteor showers in July, the observation conditions for several planets (except Mercury) are quite good. Among them, Venus, Mars, and Saturn appear in the southwestern sky at sunset, and their angular distances from each other are gradually decreasing. Jupiter rises from the east at around 22:00, with better observation conditions in the latter half of the night.
Important Astronomical Phenomena in July 2010
1st, 09:00: Neptune in conjunction with the Moon, Neptune 5^\circ South of the Moon
4th, 04:00: Uranus in conjunction with the Moon, Uranus 7^\circ South of the Moon
4th, 09:00: Jupiter in conjunction with the Moon, Jupiter 7^\circ South of the Moon
6th, 09:00: Uranus stationary
6th, 19:00: Earth at aphelion
10th, 11:00: Venus in conjunction with Regulus, Venus 1^\circ North of Regulus
12th, 04:00: Total Solar Eclipse
13th, 09:00: Mercury in conjunction with the Moon, Mercury 4^\circ North of the Moon
15th, 09:00: Venus in conjunction with the Moon, Venus 6^\circ North of the Moon
16th, 13:00: Mars in conjunction with the Moon, Mars 6^\circ North of the Moon
17th, 03:00: Saturn in conjunction with the Moon, Saturn 8^\circ North of the Moon
24th, 12:00: Jupiter stationary
28th, 07:00: Mercury in conjunction with Regulus, Mercury 0.3^\circ South of Regulus
28th, 15:00: Neptune in conjunction with the Moon, Neptune 5^\circ South of the Moon
31st, 11:00: Uranus in conjunction with the Moon, Uranus 6^\circ South of the Moon
31st, 17:00: Jupiter in conjunction with the Moon, Jupiter 7^\circ South of the Moon
Moon Path and Phases
1st, 18:00: Moon at apogee
4th, 23:00: Last Quarter Moon
12th, 04:00: New Moon
13th, 19:00: Moon at perigee
18th, 18:00: First Quarter Moon
26th, 10:00: Full Moon
29th, 08:00: Moon at apogee
July 10: Venus Conjunction Regulus
Entering July, observation conditions for Venus remain good. Although it has not reached the greatest eastern elongation of this synodic period, the altitude of Venus at sunset has begun to decrease. The main reason for this phenomenon is the difference in declination. As the planet among the inferior planets that is further from the Sun, Venus is observable for much longer than Mercury. For observers in the Northern Hemisphere, if the declination of Venus is higher than that of the Sun during elongation, its altitude at sunrise or sunset will be higher, providing better observation conditions. Conversely, if the declination of Venus is lower than the Sun’s, observation conditions at elongation might be worse than during the periods before or after. The greatest eastern elongation for Venus this time occurs on August 20. Since its declination will be about 20^\circ lower than the Sun’s at that time, even though the angular distance reaches 46^\circ, its altitude at sunset will only be about 18^\circ. For this appearance of Venus in the evening sky, the period with the highest altitude at sunset was in late May, reaching 27^\circ.
Although its altitude at sunset is gradually decreasing, the brightness of Venus continues to increase, reaching magnitude -4.2 in July. Appearing in the low southwestern sky at dusk with this brightness, many people will surely mistake it for an airplane, a kite, a balloon, or something else.
On the evening of July 10, a relatively faint star will appear near bright Venus. This is \alpha Leonis, known in ancient China as Regulus. It is a star that emits a pale yellow light and is located only about half a degree from the ecliptic. Therefore, conjunctions with planets or occultations by the Moon occur frequently. In this instance, the closest angular distance between Venus and Regulus is only 1^\circ. Of course, in actual space, the distance between the two is vast: one is an inferior planet, and the other is a star approximately 77 light-years away from the Solar System. In terms of brightness, Regulus cannot be compared with Venus, as its visual magnitude is only about +1.4.
In the following days, another astronomical event related to Venus is the Venus-Moon conjunction on July 15. The closest angular distance between bright Venus and the crescent moon is about 6^\circ, occurring at 09:00 that morning. However, this time is clearly not suitable for observation by astronomical enthusiasts in China. By sunset that evening, the angular distance between the two will have reached nearly 10^\circ. Because their altitude is not high and Mars and Saturn are nearby to join the scene, it is a good opportunity to take photographs with terrestrial landscapes.
July 12: Total Solar Eclipse
A total solar eclipse can be described as the most spectacular astronomical phenomenon. The probability of it occurring on Earth is about twice every three years. Within the three years of 2008, 2009, and 2010, three consecutive total solar eclipses occurred on Earth. I believe the previous two total solar eclipses must have been unforgettable for many. Fortunately, the paths of totality for those two eclipses passed through China—one in the Northwest region and one in the Yangtze River basin. Regrettably, the total solar eclipse on July 12, 2010, cannot be observed from China.
[Click to view Map: 2010-07-12 Total Solar Eclipse Map (GIF Format)]
[Click to view Animation: 2010-07-12 Total Solar Eclipse Animation (GIF Format)]
The path of totality for this eclipse begins in the vast waters of the South Pacific, passes through a few islands, and ends at the southern tips of Chile and Argentina in South America. Since the path of totality is entirely in the Southern Hemisphere and more than 90% is over the ocean, it is not easy for Chinese astronomical enthusiasts to travel there to witness it. At the same time, most areas where a partial solar eclipse is visible are also in the Pacific Ocean. The partial eclipse on the western side of the path begins at 01:10 Beijing Time on July 12, and the partial eclipse ends on the South American continent at 05:57. You may notice that in Universal Time (UT), this eclipse occurs on July 11. Therefore, in reports from foreign media, the date of the eclipse is listed as July 11.
At the southern tip of the South American continent, the conditions for viewing the total solar eclipse are poor, as it occurs during a "sunset with eclipse," and the observation effect cannot be guaranteed. Therefore, observing from there is not the best choice. In the middle section of the eclipse path, where the Sun’s altitude is higher during the eclipse, there are mainly several islands in the South Pacific. Among the larger ones are Mangaia Island in the Cook Islands, Tahiti in French Polynesia, and Easter Island. On Mangaia Island, the Sun’s altitude at maximum eclipse is only 14^\circ, and the totality duration is about 3 minutes and 20 seconds. Tahiti is located at the edge of the totality path, with the Sun at 22^\circ at maximum eclipse. The most ideal observation site is Easter Island, located 3,500 kilometers west of the Chilean coast.
On Easter Sunday in 1722, a Dutch merchant ship landed here for the first time, giving the island its name. The indigenous Polynesian people call it the "Navel of the World." Miraculously, within a 2,000-kilometer radius of the island, there are no other inhabited islands or landmasses. Easter Island has an area of only 163 square kilometers and is a volcanic island formed about a million years ago by the eruption of three undersea volcanoes. It is currently under Chilean jurisdiction and has an airport to accommodate tourists from around the world. Naturally, on July 12, this place will be packed with astronomical enthusiasts and photography buffs. This isolated South Pacific island is world-famous for its hundreds of mysterious humanoid stone statues. The statues are generally 5 to 10 meters high and weigh dozens of tons, with the tallest being 22 meters and weighing 300 tons. Some statues also wear red stone hats weighing up to 10 tons. These statues, called "Moai" by the locals, were carved from dark basalt and tuff, and some even have eyes inlaid with shells, looking very spirited. One can imagine that when the most spectacular total solar eclipse meets these giant stone statues, it will surely be a heart-pounding and blood-boiling experience. Here, the Sun’s altitude at maximum eclipse is 40^\circ, and totality lasts for nearly 4 minutes and 49 seconds.
Although traveling to the South Pacific is quite expensive for astronomical enthusiasts from most countries, and according to historical meteorological data, the cloud cover rate in most areas within the totality path is above 50% (with Easter Island as high as 60%), this total solar eclipse has still received widespread attention. Many foreign enthusiasts have already planned to travel for observation. Since China has experienced total solar eclipses for two consecutive years, most friends will have to reluctantly give up due to the great expense of traveling across the ocean.
Dynamics of the Sun and Five Planets
<Notes>
1) Observation time (local time): Late June—23:00; Early July—22:00; Late July—21:00
2) Observation site set at 40^\circ North Latitude.
3) Planetary positions are for the 15th of this month at 22:00.
Sun
At the beginning of the month, the Sun’s apparent Right Ascension and
Declination are 06h 39.5m and +23^\circ
07.7'.
At the end of the month, the Sun’s apparent Right Ascension and
Declination are 08h 40.5m and +18^\circ
20.5'.
This month, the Sun moves from Gemini to Cancer.
On the 12th at 04:00, a total solar eclipse occurs. The path of totality
starts in the western South Pacific, passes through eastern Oceania and
southern Chile, and ends in southern Argentina. It is not visible in
China.
Moon
The times for the Moon passing apogee, perigee, and apogee are: July 1,
18:00; July 13, 19:00; and July 29, 08:00, respectively. Last Quarter:
4th, 22:35; New Moon: 12th, 03:40; First Quarter: 18th, 18:11; Full
Moon: 26th, 09:37.
Mercury
Evening star. Located low in the northwestern sky at sunset, difficult
to observe. On the 13th at 09:00, Mercury is in conjunction with the
Moon, 4^\circ North of the Moon. On the
28th at 07:00, Mercury is in conjunction with Regulus, 0.3^\circ South of Regulus.
Venus
Moves from Cancer into Leo. Evening star. At sunset in early July, it
moves from the northwestern sky to the southwestern sky, further away
from the Sun. However, the declination of Venus is increasingly lower
than that of the Sun. Its altitude at sunset drops daily from 25^\circ to 21^\circ. Its brightness is about magnitude
-4.2, and observation conditions remain
good. On the 10th at 11:00, Venus is in conjunction with Regulus, 1^\circ North of Regulus. On the 15th at
09:00, Venus is in conjunction with the Moon, 6^\circ North of the Moon.
Mars
Moves prograde from Leo into Virgo, further approaching the Sun. It is
located in the southwestern sky at sunset. Its setting time gradually
moves earlier to around 22:00. It is visible in the first half of the
night, but the observable time is decreasing. Its brightness is about
magnitude +1.3. On the 16th at 13:00,
Mars is in conjunction with the Moon, 6^\circ North of the Moon.
Jupiter
Located in Pisces. On the 24th, Jupiter becomes stationary and changes
from prograde to retrograde motion. In July, Jupiter’s rising time from
the east continues to move earlier to around 22:30. Its brightness is
magnitude -2.6. The latter half of the
night is a good time to observe Jupiter. On the 4th at 09:00, Jupiter is
in conjunction with the Moon, 7^\circ
South of the Moon.
Saturn
Moves prograde in Virgo. Visible in the southwestern sky at sunset. Its
brightness is about magnitude +1.1. It
sets at approximately 22:30. The first half of the night is a good time
to observe Saturn, but the observation window is getting shorter. On the
17th at 03:00, Saturn is in conjunction with the Moon, 8^\circ North of the Moon.
Uranus
Located in Pisces. Brightness magnitude 5.8. On the 6th at 09:00, Uranus
is stationary. On the 4th at 04:00, Uranus is in conjunction with the
Moon, 7^\circ South of the Moon. On the
31st at 11:00, Uranus is in conjunction with the Moon, 6^\circ South of the Moon.
Neptune
Located in Aquarius. Brightness magnitude 7.8.
(Content translated and adapted from: www.skylook.org, with thanks)
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