Skywatchers will have excellent opportunities for the next several nights to see the Comet NEOWISE — making what is believed to be its first earthly visit in about 7,000 years — and the International Space Station.

The space station makes its next appearance over Philadelphia at 10:03 p.m. Thursday, zipping along at a brisk 17,500 mph from west to northeast, followed by a cameo appearance at 11:44 that will last under a minute.

NASA astronauts Chris Cassidy (right) and Robert L. Behnken during an interview two weeks ago about the space station. They'll be outside the craft doing repair work Thursday.
AP
NASA astronauts Chris Cassidy (right) and Robert L. Behnken during an interview two weeks ago about the space station. They'll be outside the craft doing repair work Thursday.

It also will be visible for the next several nights. Clouds permitting, it can be seen clearly without binoculars or telescopes, and might look like an ultra-speeding jet or one quite-brilliant star.

Meanwhile, NASA astronauts Chris Cassidy and Robert Behnken were scheduled to do some battery-replacement work outside the station on Thursday and Tuesday.

While their handiwork won’t be visible from the ground, NASA is providing live TV coverage on its website. This is a little more complicated than replacing flashlight batteries, so it could take up to seven hours.

The station, which has been up there for two decades, is host to a variety of experiments. It is also being used to analyze the impacts of longer-term spaceflight on the human body, and after weeks of isolation, many us might envy all that weightlessness.

A few hours before the space station sightings, comet NEOWISE will be the star attraction, although don’t expect a flash of brilliance, even though it’s moving about 144,000 mph, or nine times faster than the space station.

It has been appearing in a large part of the northern hemisphere around daybreak, and this week that ice-ball from outer space has become visible — with binoculars, anyway — at dusk.

NASA says it will be showing up progressively higher in the sky in the coming days; look toward the northwest.

“We still have to wait for another very bright comet, what astronomers call a great comet,” says EarthSky.org, but it describes NEOWISE, as “a wonderful binocular comet.”

It’s at least possible that NEOWISE will end the wait and blossom into a great comet, Emily Kramer, with NASA’s Jet Propulsion Laboratory, said at a briefing Wednesday afternoon, but “comets are notoriously hard to predict.”

The comet takes its name from the space-observation system that discovered it.

If you miss it this time around, not to worry. If all goes well, it should return about 8900, give or take a few years.

But NASA’s Joe Masiero cautioned that they do tend to lose some brightness over the years.