The sky of Tokyo, Calendar, Planets (July, 2017)
The sky of Tokyo
Calendar (July)
| 1 | First Quarter Moon |
| 4 | Earth passes aphelion |
| 9 | Full Moon |
| 17 | Last Quarter Moon /Ocean Day [Umi-no-hi](national holiday) |
| 23 | New Moon |
| 25 | Occultation of Mercury |
| 27 | Mars at conjunction |
| 30 | Greatest Eastern Elongation of Mercury / Aquarid δ (Delta) Meteor Shower peaks around this time (The best visibility is after midnight for 6~7 days around this date. About 5 meteors per hour are expected. Conditions are good after the Moon sets around Midnight.） |
| 31 | First Quarter Moon |
The days for the peak activities of the meteor showers are based on the predictions of IMO（International Meteor Organization).
Planets
- Mercury
- Mercury is positioned low in the western sky just after sunset. From the beginning to the middle of the month, its apparent location is close to the Sun making it unsuited for observation. Mercury reaches its greatest eastern elongation on the 30th, but its elevation is not even 10 degrees at 30 minutes before sunrise, making observation difficult.
- Venus
- Venus shines brightly low in the eastern sky before sunrise. Its brightness is -4.1 to -4.0 magnitude.
- Mars
- Located in the constellation Gemini at the beginning of the month, Mars moves east. In the middle of the month it moves into the constellation Cancer. Its apparent location is close to the Sun making it unsuited for observation. Mars reaches conjunction on the 27th, after that it is positioned low in the eastern sky before sunrise.
- Jupiter
- Located in the constellation Virgo, Jupiter can be seen in the southwestern sky after sunset. At the end of the month it sets around 22:00 as seen from Tokyo. Its brightness is -2.1 to -1.9 magnitude.
- Saturn
- Located in the constellation Ophiuchus, Saturn can be seen in the southeastern to southern sky after sunset. Its brightness is 0.1 to 0.2 magnitude. July is still a good time to observe Saturn.
Source: Ephemeris Computation Office, NAOJ
With the “Sky Viewer” you can easily explore the appearance of a typical urban night sky (planets and constellations are visible). The Celestial Phenomena section of the glossary explains the planetary phenomena terms: greatest elongation, opposition, conjunction, stationary, etc.