The dwarf blue sheep or dwarf bharal Pseudois schaeferi is an endangered species of caprid found in China Proper and Tibet. It inhabits low, arid, grassy slopes of the upper Yangtze gorge in Batang County of the Sichuan Province, and a small part of the Tibet Autonomous Region, where it is known by the local name rong-na.

Originally given subspecific status to the bharal (Pseudois nauyar), morphological research conducted in the 1970s led it to be considered a distinct species. However, recent molecular analysis has shown the difference between the two species is slight, and suggests it should be treated as a subspecies of the bharal.

The dwarf blue sheep differs from the bharal primarily in size, with adult males weighing around 35 kg, half as much as the bharal. Less sexual dimorphism occurs in this species, and females of the two species are very similar. Its coat is a steely grey with a silvery sheen, with darker general colouration than the bharal, and the horns of the male are smaller, thinner and more upright, with no inward curl.

The bharal or Himalayan blue sheep or naur, Pseudois nayaur, is a caprid found in the high Himalayas of Nepal, Tibet, China, India, Pakistan, and Bhutan. Its native names include bharal, barhal, bharar and bharut in Hindi, na or sna in Ladakh, nabo in Spitian, naur in Nepali and na or gnao in Bhutan.

The bharal has horns that grow upwards, curve out and then towards the back, somewhat like an upside down mustache.

The bharal was also the focus of George Schaller's and Peter Matthiessen's expedition to Nepal in 1973. Their personal experiences are well documented by Matthiessen in his book, The Snow Leopard. The bharal is a major food of the snow leopard.

The dwarf blue sheep (P. schaeferi) is sometimes considered to be a subspecies of the bharal.

The rutting of the bharal starts in towards late November and continues until mid-January. During the rut male bharal use multiple strategies for mating. Namely: Tending, Blocking and Coursing The young are born in late June and July.

Bharal are mainly grazers but during times of scarcity of grass they have the plasticity to switch to herbs and shrubs A high degree of diet overlap between livestock (especially donkeys) and bharal, together with density-dependent forage limitation, results in resource competition and a decline in bharal density.

Carl Edward Sagan ( /ˈseɪɡɪn/; November 9, 1934 – December 20, 1996) was an American astronomer, astrophysicist, cosmologist, author, science popularizer, and science communicator in astronomy and natural sciences. He published more than 600 scientific papers and articles and was author, co-author or editor of more than 20 books. He advocated scientifically skeptical inquiry and the scientific method, pioneered exobiology and promoted the Search for Extra-Terrestrial Intelligence (SETI).

Sagan is known for his popular science books and for the award-winning 1980 television series Cosmos: A Personal Voyage, which he narrated and co-wrote. The book Cosmos was published to accompany the series. Sagan wrote the novel Contact, the basis for a 1997 film of the same name.

Carl Sagan was born in Brooklyn, New York, to a Ukrainian Jewish family. His father, Sam Sagan, was an immigrant garment worker from Kamenets-Podolsk, Ukraine; his mother, Rachel Molly Gruber, a housewife. Carl was named in honor of Rachel's biological mother, Chaiya Clara, in Sagan's words, "the mother she never knew." Sagan graduated from Rahway High School in Rahway, New Jersey, in 1951.