Skylights featured on Astronomy Picture of the Day

Scout Report Selection Webivore Selection SpaceCareers Selection

Skylights featured three times on Earth Science Picture of the Day: 1 , 2 , 3 , 4 .

Panoramic clouds

Photo of the Week.. Panoramic views of a cloudscape shows how its appearance changes according to the direction to the Sun; on top you look away from the Sun, while on the bottom you look more toward it.

Astronomy news for the week starting Friday, June 18, 2004.

This vacation version of Skylights covers the next three weeks. The next Skylights will appear on Friday, July 16.

During this extended interval, the Moon waxes from first quarter (which takes place on Friday, June 25, about Moonrise), through gibbous to full on Friday, July 2 (about the time of Moonset). This full Moon falls just to the east of the Winter Solstice in Sagittarius, and is the most southerly of the year. The Moon then wanes through gibbous to third quarter, which occurs just past midnight the night of Thursday, July 8, and then through the morning crescent almost to new again, allowing about three quarters of the lunar cycle to be admired. The period from Tuesday, July 13, to Thursday, July 15, is especially interesting, as the crescent Moon plunges through and past northern Taurus, which has now cleared the Sun. We also see the Moon swinging from perigee (closest to the Earth) the day before full phase to apogee (farthest) on Wednesday, July 14.

This three week period is filled with events. Venus is back with us, having popped up in the morning sky. Look for it below the waning crescent Moon around the beginning of dawn the morning of Tuesday, July 13th. The following morning it will appear to the right of the even thinner Moon. The brilliant planet will make a nice appearance in Taurus around this time near the star Aldebaran and the Hyades cluster. Quickly climbing the morning sky, Venus reaches greatest brilliance for this apparition on Wednesday, July 14. It will then be with us the rest of the year, not disappearing into twilight until after the beginning of 2005.

Venus's brother planet Mercury then takes the stage. Though the event will be difficult to see deep in evening twilight, Mercury will come into close conjunction with Mars the evening of Saturday, July 10, when the two will be but two-tenths of a degree apart. Mars is so far away now that it will be significantly fainter than Mercury. Binoculars will be needed. While still dominating the early night sky, Jupiter now sets in mid evening, leaving us with no planetary show at all until Venus comes up. Saturn is now completely gone, as it passes conjunction with the Sun on Thursday, July 8.

Again, Earth makes news, as it passes its orbital aphelion, where it is farthest from the Sun, on Monday, July 5, about the time of sunrise in North America. At that time, it will stand 94.508 million miles from the Sun (152.095 million kilometers), 1.7 percent farther than average. That we are farthest from the Sun in the middle of northern Summer clearly shows that distance has little to do with the seasons, which are caused entirely by the 23.4 degree tilt of the Earth's axis against the perpendicular to the orbit.

The stars of Spring are now being shooed away by those of Summer. Watch for the progression of a set of five marvelous northern constellations that begins with Bootes, the Herdsman, which is well marked by the luminary of the northern hemisphere, Arcturus. To the east of Bootes, we see Corona Borealis (the Northern Crown), then Hercules, Lyra with brilliant white Vega, and finally Cygnus (the Swan) topped at the north by Deneb. Far to the south, immediately below Hercules, lies Scorpius (the Scorpion), while to the east of Scorpius is Sagittarius (the Archer). When the Moon is out of the way look from Cygnus on down through Aquila (the Eagle) and Scutum (the Shield) to admire the wonderful Summer Milky Way.
Valid HTML 4.0!