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.