Sky & Telescope | 2017 Aug 30
When astronomer Bobby Bus discovered an asteroid passing through the inner solar system on March 2, 1981, it was bright enough to record in his telescope's photos despite being more than 145 million miles away. This week that same body, now bearing the catalog number 3122 and named to honor Florence Nightingale, is cruising by us at a distance of just 4.4 million miles (7 million km). That's closer than it's been since 1890 or will be again until at least 2500.
- During late August and early September, the near-Earth asteroid 3122 Florence passes Earth as close as 4.4 million miles from Earth. It will be bright enough to spot in modest backyard telescopes. Note that the labeled dates on this chart mark the asteroid's location at 11 p.m. Eastern Daylight Time; adjust to your time zone accordingly. Credit: Sky & Telescope
Florence will not pose any danger to Earth, but all this week the asteroid will appear as bright as a 9th-magnitude star. "Despite some interference from moonlight, 3122 Florence should be fairly easy to spot in even modest backyard telescopes," notes Kelly Beatty, a senior editor at Sky & Telescope magazine.
To locate Florence, you'll need an accurate sky chart that plots the asteroid's motion among the background stars night to night. The best time to view will be late evening, when it's high overhead. Although Florence reaches peak brightness (magnitude 8.7) late on Thursday night (August 31st and early on September 1st), it should remain nearly this bright for several days before and afterward. ...