This symbol was created in 1987 by a Brazilian Esperantist to mark the centenary of the creation of Esperanto. On the other hand, this new symbol is jokingly called "the melon" () by some. Most Esperantists, however, continue to hold the "verda stelo" dear as a symbol of international or supranational solidarity, and regard the preference of one symbol over another as a purely personal choice. At most Esperanto congresses, all three main symbols can be seen in use on displays or being worn as badges. Sometimes, Esperanto travelers will display the flag, wear a badge with one of the above symbols, or even wear green clothes, to make themselves known to other Esperanto speakers. In 1905, delegates to the first conference of Esperantists at Boulogne-sur-Mer, unanimously approved a version, differing from the modern only by the superimposition of an "E" over the green star. Other variants include that for Christian Esperantists, with a white Christian cross superimposed upon the green star, and that for Leftists, with the color of the field changed from green to red. On December 15, 2009, the Esperanto flag flew on the Google home search page "Google" logo to mark L. L. Zamenhof's 150th birthday. The flagstaff was the "L" of the search-company name. One hypothesis of the red star as a symbol of socialism relates to an alleged encounter between Leon Trotsky and Nikolai Krylenko. Krylenko, an Esperantist, was wearing a green-star lapel badge; Trotsky enquired as to its meaning and received an explanation that each arm of the star represented one of the five traditional continents. On hearing this, he specified that a similar red star should be worn by soldiers of the Red Army.