Welcome to the website for the 99942 Apophis 2021 Observing Campaign. Our intention is to provide a central clearinghouse for basic information about the near Earth asteroid Asteroid 99942 Apophis and about the observations that will be obtained during its upcoming 2021 apparition. Although the 2021 apparition is not very close to the Earth, Apophis is of particular interest because in 2029, it will approach to within ~40,000 km.

This campaign is organized by the International Asteroid Warning Network (IAWN) to exercise the observing resources and characterization capabilities that may be applied to a near-Earth object on a reasonably short timescale. It is the third such campaign to be organized by IAWN, the first being organized for the 2012 TC4 close approach in October of 2017.

This site will contain background information about Asteroid 99942 Apophis, a list of observations that are planned/scheduled/obtained, and status reports on the events leading up to the encounter. We will also produce an email list where updates can be broadcast to subscribers. Experienced observers may contact Campaign Lead Dr. Vishnu Reddy to subscribe.


  • REMINDER: Deadline Jan 31, the Planetary Defense Conference abstracts due! The PDC will include a session on Characterization Opportunities from NEO Close Approaches.
  • 21 Jan 2021: The campaign exercise, to observe Apophis as a "new" object to test the followup and calculation activities is going well with participants meeting every other week via telecon.
  • 17 Jan 2021: Dave Balam provided 2 orbit stacks taken with the Canadian NEOSSat.
  • 7 Jan 2021: David Polishook submitted an animation from Wise Observatory.

Summary of the 2021 Apparition

Asteroid 99942 Apophis is a near-Earth asteroid

  • Closest approach to the Earth occurs on 2021 Mar 06 1:06 UT
    • Speed with respect to Earth is 4.658 km/sec
  • Geocentric Distance (current best value - JPL#199)
    • 0.1126 au
    • 43.8 Lunar distances
    • 1.685×107 km


Current estimates suggest it should peak around mag 16.2 at closest approach.

Observing conditions (for observations at visible wavelengths)

The 2021 apparition is not particularly close to the Earth, so conditions do not change dramatically around close approach. The viewing geometry is such that it is visible from mid-latitudes (both North and South) for several months around close approach.