<p>Current estimates put Apophis's diameter around <a href="http://www.esa.int/Our_Activities/Space_Science/Herschel_intercepts_asteroid_Apophis" rel="nofollow noreferrer">325 m</a> and its 2029-04-13 approach about <a href="https://newton.spacedys.com/neodys/index.php?pc=1.1.8&amp;n=99942" rel="nofollow noreferrer">38000 km</a> from the center of the Earth. I figure an angular size &lt;= 2 arcsec, almost starlike even if you manage to track it in a telescope.
<a href="http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&amp;body_group=sb&amp;sstr=99942" rel="nofollow noreferrer">Ephemerides</a> show it at apparent magnitude 3.5 or so just before closest approach - visible but not outstanding to the unaided eye at night - and spending about 36 hours within 1 lunar distance of the Earth.</p>

CC BY-SA 4.0
2019-06-23T02:17:40.923Z
I'm not sure if the Hubble telescope will be operational then, but it would be a few dozen pixels wide at that size and so nicely imageable in visible light. fyi I've just asked [Has Hubble ever been used to try to image a near Earth asteroid?](https://astronomy.stackexchange.com/q/32388/7982)
uhoh
CC BY-SA 4.0
2016-04-26T06:09:06.547Z
2019-06-22T16:42:41.907Z
2019-06-22T16:42:41.907Z
Mike G
<p>How big will Apophis appear in the sky at its closest point of approach in 2029? Will it compare  to the moon? How long will it linger as it passes?</p>

<observational-astronomy><amateur-observing><asteroids>
How big will Apophis appear?
Anthony McCloskey
# How big will Apophis appear?

(Asked by: username_0 on 2016-04-26)

How big will Apophis appear in the sky at its closest point of approach in 2029? Will it compare to the moon? How long will it linger as it passes?

**Tags:** observational-astronomy, amateur-observing, asteroids


---

## 1 answers

### Answer by username_1 on 2016-04-26. Score: 5 | Accepted answer

Current estimates put Apophis's diameter around [325 m](http://www.esa.int/Our_Activities/Space_Science/Herschel_intercepts_asteroid_Apophis) and its 2029-04-13 approach about [38000 km](https://newton.spacedys.com/neodys/index.php?pc=1.1.8&n=99942) from the center of the Earth. I figure an angular size <= 2 arcsec, almost starlike even if you manage to track it in a telescope.
[Ephemerides](http://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=99942) show it at apparent magnitude 3.5 or so just before closest approach - visible but not outstanding to the unaided eye at night - and spending about 36 hours within 1 lunar distance of the Earth.

> **Comments:**
> **username_2**: I'm not sure if the Hubble telescope will be operational then, but it would be a few dozen pixels wide at that size and so nicely imageable in visible light. fyi I've just asked [Has Hubble ever been used to try to image a near Earth asteroid?](https://astronomy.stackexchange.com/q/32388/7982)  

---

