http://www.sr.bham.ac.uk/xmm/images/xray/blackhole_300_300.jpg

http://antwrp.gsfc.nasa.gov/apod/image/0607/rsoph_pparc.jpg

http://www.parssky.com/News/my_documents/upload-new/uploads/1E1_preview_image.jpg

http://www.iaas.ir/userfiles/image/image008.jpg