Mike Branch helps customers shop for a Halloween masks at Fantasy Costumes on October 28, 2011 in Chicago, Illinois. The store, which had long lines at the registers at 4 AM this morning, is open around the clock through Halloween to help keep up with customer demand. Retailers nationwide are expecting record sales for Halloween merchandise this year with shoppers spending close to $7 billion dollars to celebrate the holiday. (Photo by Scott Olson/Getty Images)

An Iraqi Kurdish Peshmerga takes part in a graduation ceremony at the Zakho military academy in the Iraqi Kurdish town of Zakho, some 500 kilometres north of Baghdad, on January 30, 2018. (Photo by Safin Hamed/AFP Photo)

“The Sloan Digital Sky Survey III (SDSS-III) has released the largest-ever three-dimensional map of massive galaxies and distant black holes, which will help astronomers explain the mysterious “dark matter” and “dark energy” that scientists know makes up 96 percent of the Universe”. – SDSS-III

Iraqi security forces ride in vehicles travelling to Mosul to fight against militants of Islamic State at an Iraqi army base in Camp Taji in Baghdad, February 21, 2016. (Photo by Ahmed Saad/Reuters)

Russian Tu-95MS strategic bombers fly in formation during rehearsals for the Victory Day military parade, with St. Basil's Cathedral seen in the foreground, in central Moscow May 5, 2015. Russia will celebrate the 70th anniversary of the victory over Nazi Germany in World War Two on May 9. (Photo by Tatyana Makeyeva/Reuters)

A labourer packs incense in preparation for Tet, the traditional Vietnamese lunar new year, in Hong Chau village, outside Hanoi January 29, 2015. Tet is from February 14 till 24. (Photo by Reuters/Kham)

Hundreds of green bicycles are prepared as 960 of them await riders for the new year gala at the Temple of Heaven Park on December 29, 2011 in Beijing, China. Annual New Year countdown ceremony will be held at the park on December 31. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

The book “Elektroschutz in 132 Bildern” (Electrical Protection in 132 Pictures) was published in Vienna in the early 1900s by a Viennese physician named Stefan Jellinek (1878-1968, a founder of the Electro-Pathological Museum). The pictures are nice and direct and unambiguous; they teach, graphically, that the surest way to kill yourself with electricity is to form a complete path from source (usually the bright red arrow) to ground (the screened back, pink arrow). Arrowheads provide the path for current flow. (Photo by The Vienna Technical Museum)