January 20, 1999
2. Uranus is never easy to see and today it is definitely impossible to see the seventh planet as it is in conjunction with the sun. This configuration places Uranus on the opposite side of the sun, 1.9 billion miles from Earth.
5. For many planetary fans, the evening combination of Venus, Jupiter and Saturn is satisfying enough. If you feel a need to see Mars, you'll have to get up early in the morning. Tomorrow might make it worthwhile, as Mars will be high above the southern horizon at 5:00 or 6:00 in the morning. Off to Mars' right is the bright star of Virgo, Spica; the waning moon crowns this little trio on the border between Virgo and Libra.
7. The planets' orbits in the solar system are not perfectly flat in the solar system plane; most of them are tipped by slight amounts. A few, like Pluto, wander far above and below the solar system plane. Both Mars and the moon are a few degrees north of the ecliptic today, and quite close to each other. They will rise in Virgo after 1 a.m., a little past the time of their closest approach.
8. At last quarter phase, the moon is exactly 90 degrees west of the sun. By the time the moon reaches that precise point in its orbit, 5:58 a.m. today, it will be in the constellation Libra, poised above the southern horizon. Mars is off to the west, or right of the moon as you face south.
14. The moon is just a waning sliver in the east this morning, with a small and faint companion. Neptune is south of the moon by a distance of about 3 lunar diameters. Uranus has swung around the sun and is positioned about halfway between the moon and sun, obscured by the dawn glow.
15. Oh, for a view below the horizon early tomorrow morning! The sun is flanked by Mercury, Venus and Jupiter on one side (the planets we see trailing the sun into the west at sunset) and Neptune and Uranus on the other side. Most exciting of all, the moon will be smack-dab in front of the sun at 12:39 tomorrow morning. For folks lucky enough to have the sun and moon above the horizon at that time, there will be a nice annular eclipse of the sun.
16. A new moon brings a new month to many traditional calendars. This day happens to be the first of the year 4636 in the Chinese calendric tradition. This is the year of the tiger in the twelve-year rotating cycle.
17. Tomorrow is a special anniversary for Kansas astronomers, the 69th anniversary of the discovery of Pluto by Kansan Clyde Tombaugh. In all those years, Pluto has not even traveled a third of its path around the sun!
18. There are few sights more beautiful than the evening star near a very young moon. The term "evening star" is loosely applied to any bright planet visible in the evening western sky. Because Venus is never very far from the sun's position, it is essentially always an evening or morning star. This evening will be enhanced by Jupiter between Venus and the waxing crescent moon. Saturn stands above this trio, about 20 degrees above the conjoined moon, Venus and Jupiter.
20. The moon is on its way towards first quarter phase, lighting the evening sky a little more each night. The moon happens to be at perigee today, the point of its orbit closest to Earth. This is the anniversary of John Glenn's orbital flight aboard Friendship 7 in 1962, the very first orbital flight by a U.S. astronaut.
22. The moon will be at first quarter phase this evening at 8:43 p.m. At this phase, the moon presents itself nicely above the southern horizon at sunset. You can monitor the moon's progress through the zodiac constellation Taurus tonight and tomorrow. The very bright star in the "flying-V" shape of Taurus is the kingly star, Aldebaran.
23. A planetary conjunction well worth your attention is scheduled for this evening. Venus and Jupiter will be very close to each other this evening between sunset and about 7:30 when this bright pair also sinks below the western horizon. Venus is a smaller planet than Jupiter but much, much closer to Earth and it is considerably brighter as a result.
25. It's bound to happen - the complete cycle of lunar phases takes a little over 29 days, and February is just a tad shorter than a lunar month. So, we're short a lunar phase this February and it happens to be the full moon. January had two full moons as will March.
28. Here's a huge question about the year 2000 - will there be a leap day next February, or not? The Earth takes 365.242 days to orbit the sun. Adding a day every fourth year to the calendar would make the year 365.25 days long on average, a bit too long. If century years are omitted from the leap-day recipe, the day length drops back to 365.24 days, almost right. The fine tuning of the Gregorian reform stipulates that century years should not be leap years, unless they are divisible by 400. So, 2000 will have 366 days.