SKYLIGHTS

Astronomy news for the week starting Friday, June 15, 2001.

The Moon disappears from the sky toward the end of the week, as it passes its new phase on Thursday, the 21st. As the lunar crescent wanes during the early morning hours, it will make a nice configuration with brilliant Venus the morning of Monday, the 18th. The following morning, Tuesday the 19th, the slimming crescent will be found beneath the Pleiades star cluster in Taurus and up and to the right of Saturn, which is now just clearing the glare of the Sun. Little Mercury, however, is not so lucky (or perhaps it is we who are not), as this smallest of the inner planets passes inferior conjunction with the Sun on Saturday, June 16.

The big date takes place 5 days later. First, the Sun will cross the Summer Solstice in Gemini at 2:38 AM Central Daylight Time (1:38 AM EST, 12:38 PST), marking the first day of astronomical summer in the northern hemisphere, astronomical winter in the southern. At that moment, the northern end of the Earth's axis will be tipped in the direction of the Sun, the Sun will shine overhead at the Tropic of Cancer, will be circumpolar (not setting) at the Arctic Circle, and will not rise at the Antarctic Circle (technically anyway: atmospheric refraction and the extended diameter of the Sun will still make it visible). The Sun will then be as far north as it can get, 23.4 degrees from the equator. For the next 6 months, solar movement will be southerly.

On the same date, Thursday the 21st, the new Moon will exactly cover the Sun to produce a total solar eclipse that will be visible along a path through the South Atlantic Ocean and across southern Africa. None of it will be visible in North America, though eastern South America will see a bit of a partial eclipse. The geometry of eclipses requires at least two solar eclipses a year. The June event is the only total eclipse. One other, on December 14, is annular (that is, the Moon will be too far away to completely cover the Sun), and will be visible principally through the Pacific Ocean.

None of the news of the Sun can eclipse the current glory of Mars, however. Moving retrograde between Sagittarius and Scorpius, the planet is nicely up in the southeast at the end of twilight. Just look for the brightest thing you can see! Though Mars passed through opposition with the Sun on June 13, its eccentric orbit causes it to get slightly closer to us until -- again -- Thursday, the 21st, when the red planet will be 67,344,000 kilometers (41,846,000 million miles) from us, and at its best for viewing. Even a small telescope can show polar caps and dark markings. To the right of Mars is bright Antares in Scorpius. If you are not too far north, the figure of the celestial scorpion, curved tail, stinger, and all, is quite obvious.