Tens of thousands of “near-Earth objects,” or NEOs, are constantly passing near or through Earth’s orbit and have the potential to collide with our planet. Only a few of these are large enough to cause the global devastation that wiped out the dinosaurs, and none is known to be on a collision course with us. Yet the potential for disaster is there and Rick Fienberg, editor-in-chief of Sky & Telescope magazine, describes in the August issue what actions are being taken.

In 2005 the U.S. Congress directed NASA to formulate a plan to track potentially destructive asteroids and propose means to divert them from their paths if they threatened Earth. In March 2007, NASA presented a variety of possible approaches but said the cost of implementation, about $1 billion, was prohibitive and did not recommend any direct action at this time.

Proponents of an asteroid interception program, such as former Apollo astronaut Russell Schweickart, strongly criticized this course of inaction. But perhaps Fienberg makes the most telling point of all in his editorial. We have the technology available today to divert NEOs without using such movie spectaculars as nuclear bombs. If there is any chance at all that Earth one day may be devastated by an NEO, can we afford to ignore it?

Focus on the planets

Mercury makes a brief appearance on the northeast horizon about 45 minutes before sunrise as August opens. By the 8th of the month it will have disappeared in the glare of the sun.

Venus is very low in the west shortly after sunset but soon disappears as it scoots between us and the sun only to reappear low in the east just before sunrise at month’s end.

Mars rises in the northeast about an hour after midnight as the month opens and continues to brighten as the year wears on. On Aug. 7, look for Mars to the immediate lower right of the Pleiades during the early morning hours.

Jupiter reigns as a brilliant “star” in the south at twilight. The planet’s surface features and major moons are readily visible by telescope. The orange star below Jupiter is Antares in the constellation Scorpius.

Saturn is lost to view during August.

Neptune is a bluish disk in the constellation of Capricornus that can be seen high in the south around midnight using a medium telescope and the finder’s chart in the July issue of Sky & Telescope.

Uranus, a greenish disk in Aquarius, follows Neptune by about an hour and a half across the sky and can be spotted with binoculars.

August events

7 For insomniacs, there is a treat in store in the northeast around 2 a.m. where the moon forms a triangle with the Pleiades to its upper right and Mars to its lower right respectively.

11 The sun enters the constellation Leo on the ecliptic.

12 New moon, 7:02 p.m. The Perseid meteor shower peaks around this date and, with no interference from moon glow, should be one of the best shows of the year. Originating in the northeast from the constellation Perseus, the meteor stream rises in intensity from about 11 p.m. until the early morning hours when 60 or more meteors an hour may be seen. The Perseids are fast, bright, and often leave persistent trails.

17 Tonight Venus passes almost directly between Earth and sun as it makes its way into the morning sky.

19 The moon is at apogee or farthest distance from Earth today.

23 The sun enters the astrological sign of Virgo but, astronomically, is still in Leo.

28 Full moon, 6:36 a.m. The full moon of August is known as the Fruit Moon, Grain Moon, Green Corn Moon and the Sturgeon Moon. Tonight a full lunar eclipse will be seen by viewers west of the Mississippi River. For Eastern viewers, the barest hint of the eclipse will begin as dawn is brightening and the moon is dropping low in the west.

31 The moon is at perigee for the second time this month. Mars and Aldebaran are paired in the east-northeast during the early morning hours and Venus may be spotted in the east at dawn as it begins its stint as the “morning star.” Sunrise, 5:56 a.m.; sunset, 7:15 p.m.