The giant space rock dubbed Comet 21P/Giacobini-Zinner has been becoming increasingly easier to spot at night since around mid-August.
Emitting a characteristic green-blueish glow, Comet 21P has brightened by a full magnitude since last week on August 15.
Astronomer Odd Trondal in Oslo, Norway, took a 30-second-long exposure of the comet just one minute after midnight, Universal Time (UT) on Sunday, August 19.
The astronomer posted: “Note the faint nebula north of the comet’s tail at 3h 11m 01s +52º38’.”
According to Mr Trondal, the comet’s brightness has increased from magnitude 12.5 to magnitude 11.5 since he first began tracking it last week.
Another snapshot of the speeding space rock was captured on August 13 above Mayens de My in Conthey, Switzerland.
The space picture features Comet 21P passing alongside a lonely Perseid meteor near the constellation Cassiopeia.
The picture’s author, Olivier Roger Staiger, said the comet looked like nothing more than a tiny speck against the starlit sky.
Another picture of the tiny green spot of light was snapped over the small town of Tiny in Ontario, Canada, by astronomer Roman Kulesza.
But despite its minuscule appearance, Comet 21P is estimated to have a nucleus measuring about 1.24 miles (2km) in diameter.
The giant space rock is a well-known periodic comet in the solar system with an orbital path of more than 2,400 days.
Comet 21P was first spotted from Earth on December 20, 1900, by astronomer Michel Giacobini.
Astronomer Ernst Zinner spotted the very same comet 13 years later in October while observing the Beta Scuti binary star system.
Today, the comet’s trajectory around the solar system is tracked by NASA’s astronomers at the Jet Propulsion Laboratory.
According to NASA’s ephemeris calculator, Comet 21P is currently on a path that will see the space rock dip below the Earth’s orbit around the Sun.
The comet and the Earth will soon approach each other next month in the afternoon hours on September 10, UT.
During this approach the comet will come within 0.391 astronomical units (AU) of the planet or 36,422,179 miles (58,615,816.2km) from Earth.
On August 9, astronomer Rene Germain took a picture of the glowing comet over Ville-Marie in Canada.
The astronomer wrote: “Here comes Comet 21P/Giacobini-Zinner, taken with the Canon 6D camera and 127mm app refractor.
“I have 30 pictures stacked with DSS; 90 second exposes for each pictures. The head is bright in a 10 inch telescope with a faint tail.
“Saw it too with 25×100 binoculars but no tail. Very easy to locate near epsilon Cassiopea; one of the five bright star describing the constellation.”
On the night of September 3 the comet is expected to be just over one degree from the bright star Capella in the constellation Auriga.
This should make spotting Comet 21P much easier to locate at night.
Comet 21P will next come close to Earth at a similar distance of 0.36 AU on February 13, 2019.