Visible and near-infrared reflectance spectra of Sedna, Makemake, Pluto, and Eris
Spectra of four of the largest and most volatile rich Kuiper belt objects. The prominent methane (CH4) absorption lines can be seen on all objects. The weaker carbon monoxide (CO) and molecular nitrogen (N2) lines can only be detected on Pluto. Figure 1 from Brown (2012): "The compositions of Kuiper belt objects."
Original image data dated on or about December 13, 2011