Cometary brightness is difficult to predict , especially when , as in this case , it is the first known appearance of the comet ; so far C/2009 R1 is proving to be brighter than expected , so much so that Sky and Telescope retitled an online article from " Faint Comet in the June dawn " to " Comet in the June dawn " . C/2009 R1 is expected to eventually reach a brightness as high as magnitude 2 from June 30 to July 2 , 2010 , the latter date marking perihelion ; however , as it brightens , its proximity to the Sun will make it difficult to see , and it is likely to only be visible near the horizon at dawn and dusk . The exception to this will be the total solar eclipse on July 11 in the Southern Hemisphere ( visible in the South Pacific , touching land at Mangaia , Easter Island , and far southern Chile and Argentina ) , which will allow the comet to be seen during the day . The comet is notable for its " impressive green coma and long ion tail " , which spanned 5 degrees as of June 6 , 2010 , and its appearance has been likened to an " apple on a stick . " By June 13 , a second tail created by dust from the comet , was also visible , sharing the same green hue of the coma . The green colors in the coma are caused by the presence of cyanogen and diatomic carbon , while bluish hues in the ion tail are produced by positively charged carbon monoxide and carbon dioxide ions
total solar eclipse on July 11
Solar eclipse of July 11, 2010
C/2009 R1