The last week of February and first few days of March offer a rare opportunity to people at mid-northern latitudes: the chance to see the night sky's six or seven brightest objects in the night sky simultaneously 30 to 60 minutes after sunset. These are (in order of brightness).
Brightest Objects in the Night Sky to Observe:
- The Moon (seriously bright!)
- Venus (magnitude -4.3)
- Jupiter (magnitude -2.2)
- Sirius (magnitude -1.4)
- Mars (magnitude -1.2)
- Mercury (see below)
- Canopus (south of latitude 37°N)
You will need a site with an unobstructed horizon to the west (for Mercury) and east (for Mars). People who hope to see Canopus will also need an unobstructed horizon to the south.
The timing for observing the brightest objects in the night sky is determined by Mercury, which is setting in the west at dusk. The later in the evening you observe, the darker the sky will be, but the lower Mercury will be. Forty-five minutes after sunset might be a good compromise.
All the brightest objects in the night sky in the list, except for Mercury, look better as the sky grows darker. Venus, Jupiter, Sirius, and the Moon remain above the horizon for several hours after sunset, and Mars rises higher as the evening progresses, peaking around midnight.
The best dates for observing the brightest objects in the night sky are toward the end of the window of opportunity, in early March. That's because Mars appears higher in the east each evening, while Mercury remains near its highest throughout the first week of March.
However, Mercury fades during the period, starting around magnitude -1.2 in late February, fading below Canopus (magnitude -0.7) around March 3d, and fading below Alpha Centauri (magnitude -0.3) around March 5th. That ends this viewing opportunity of the brightest objects in the night sky because on evenings at this time of the year, Alpha Centauri is only visible from the Southern Hemisphere.
This opportunity is made possible by the coincidence of several factors. Venus and Jupiter are both high in the evening sky. Mercury is enjoying its best evening apparition of 2012 for northern viewers. Mars is almost at its closest to Earth for this orbit — the only time it counts among the night sky's 7 brightest objects. And this all takes place when Sirius and Canopus are near the highest in the early evening.
Canopus is visible anywhere south of latitude 37° north, assuming that you have an unobstructed southern horizon. The sky scene at right shows Canopus from latitude 34° north — roughly accurate for Los Angeles and Atlanta.
In case you're wondering, the northern limit for viewing the 6 brightest objects is around the Arctic Circle, beyond which Sirius becomes invisible. And the southern limit to achieve the feat without optical aid is around the equator. South of that, the angle of the ecliptic is so shallow that it's very difficult to spot Mercury.
However, people at mid-southern latitudes can probably see the night sky's eight brightest objects, including Alpha Centauri, 15 to 30 minutes after sunset in early March if they use binoculars, making it possible to catch both Mercury and Mars low in the twilight glow.
People all over the world should keep watching Venus and Jupiter as they approach each other during the first two weeks of March.