by Joe Cali

The NEO Asteroid (152637) 1997 NC1 will be making a relatively close passage past Earth during the last week of June and first week of July. We are expecting a flood of social media disinformation to be published. This article is factual, authoritative, and written for members of the public with no astronomy experience.

The graphic above illustrates the size of a 900m asteroid, about three times in diameter compared to the height of the Eifel Tower.

At closest approach to Earth on June 27 at 22:30 AEST, this 900m diameter asteroid will be 2.5 million km from Earth or about six times the Earth-Moon distance. Close approaches of this asteroid at approximately this distance occur once every 50 years. Next 2.5M km approaches occur in 2088, 2133, 2178. Closest approach during less favourable orbits can be as distant as 30 million km. The asteroid has an orbital period of 294 days, orbit speed of 32km/s and aphelion of 1.05 AU, perihelion of 0.68 AU. Although NASA classifies this object as an Aten-class asteroid, and it’s classified as a Potentially Hazardous Asteroid (PHA), there is no danger of collision with Earth on this orbit or subsequent orbits over the next few hundred years unless the object’s orbit is changed by some yet undiscovered, gravitational interaction that changes the orbital parameters. Although this asteroid only approaches this close once every 50 years, overall, this is not a rare occurrence. Between June 10 and July 31, 2026, about 20 asteroids sized between 25m-1.6km diameter, pass Earth at distances between 280,000 and 6 million km of the Earth.

At closest approach, the object will reach a maximum brightness of astronomical magnitude 10.5.  This is approximately 100 times fainter than can be seen by the unaided eye of someone with good eyesight under a dark country sky, and 6-15 times too faint to be seen with 50mm binoculars under the same dark sky conditions.

To see it, you would need a telescope of at least 4-5 inches diameter or larger. Even if you have a such a telescope, It is difficult to find, Because the object is constantly moving against the background stars, shifting by one full moon diameter every 40 minutes, you need to know it’s exact celestial coordinates at any particular time and be able to navigate the myriad of stars in the Milky Way in order to see it. Even in a telescope, at that distance, it will still have the appearance of a star. No surface detail will be visible.

In short, this requires some expertise to locate and a large telescope to observe it. It is not an object for the public to observe from their backyard or public lookout.

Over a period of just over two weeks, the asteroid will pass along the length of the Milky Way from near Vega on the northern horizon to near the Southern Cross well in the south.  It shifts by more than one full Moon diameter relative to the background stars every hour.

*  The author Joe Cali is a member of the AAQ Council serving as Membership Secretary in 2026. He is a trained physicist and worked in Climate Science Research at the Australian National University for 37 years until his retirement. Joe has been a keen amateur astronomer over the past five decades.  

Media use: This content may be used by media with acknowledgement of the source and without quoting extracts in a way that they change the meaning or indicate any threat to Earth or visibility from Earth.