Grace (26 Aug 2011)
"For Rene: Elenin Nearest Earth"

Hi Rene,
Yesterday, you asked about the date when Elenin would be closest to Earth.
You can refer to the website of an experienced Australian amateur astronomer, Michael Mattiazzo, at This website is also personally mentioned by Leonid Elenin, founder of the comet.
View occasional updates of comet Elenin at which is owned by Leonid Elenin himself.
C/2010 X1 Elenin
Closest to Sun on 10 Sep 2011 at 0.48AU
Closest to Earth on 17 Oct 2011 at 0.23AU
A Russian amateur astronomer, Leonid Elenin of Lyubertsy near Moscow, discovered a 19th magnitude comet on December 10, 2010, using a remotely controlled telescope situated in New Mexico, USA.
The comet will pass perihelion on September 10, 2011 at a distance of 0.48 AU, later encountering the Earth on October 17 at 0.23 AU.
The observing circumstances from Earth's perspective are highly favourable as comets are concerned. The close passage to the Sun and later close encounter with Earth are important factors in producing bright comets, especially if the solar encounter causes disruption to the nucleus, releasing dust particles.
Unfortunately the comet appears intrinsically faint (absolute magnitude 10). Intrinsically faint comets are usually gas rich and dust poor, but they do have a tendency to brighten rapidly at perihelion.
The comet is inclined only 1.8 degrees from Earths orbit thus we will observe the comet virtually edge-on throughout the apparition. This will enhance the dust tail and trail - should the comet actually be able to produce dust!
The comet may appear visible to the unaided eye at magnitude 4, when well situated in the evening sky for Southern hemisphere observers during early September 2011.
  • By mid September, it continues to brighten but is lost to evening twilight.
  • By late September, it passes 2 degrees from the Sun and should be visible through the SOHO C3 coronagraph (between Sep 23 and 29), and STEREO A&B spacecraft.
A maximum phase angle of 177 degrees is reached around September 26. Dust is very efficient at forward scattering of sunlight.
A surge of 2 magnitudes is possible if the comet is dust rich. However, the comet is not expected to be observable from the ground, and any attempts to do so will be very risky!
During early October, comet Elenin reappears in dawn skies for Northern hemisphere observers.
Southerners need to wait until mid-October before the comet is sufficiently high enough for observation, but moonlight will interfere until October 23rd.
Hope this helps. Blessings!!
I also posted a few more things at