NASA’s Space shuttle Endeavour retired from the service and was sent to a museum. 

About Endeavour:

• Endeavour was introduced as a replacement to Challenger, which exploded during launch in 1986.
• It made its first flight on May 7, 1992 on STS-49 mission. Its last mission was STS-134 in May 2011.
• Its last mission was on International Space Station assembly mission which delivered the Alpha Magnetic Spectrometer and the ELC-3 to the space station.

September 21 is World Alzheimer's Day. The day is observed to spread awareness about Alzheimer's disease across the globe.

What is Alzheimer’s disease?

Alzheimer’s disease is most common form of dementia (loss of memory). The disease, caused by the degeneration of brain cells and nerves, impacts functioning of the brain, affecting day-to-day activities in its victims. The disease is generally diagnosed in the people over 65-year age. The main symptoms include difficulty in remembering recent events which gradually develops into advance symptoms like confusion, irritability and aggression, mood swings, trouble with language, and long-term memory loss. There is no cure for the disease, which worsens as it progresses, and eventually leads to death.

About a fourth of the world's Alzheimer's patients live in India.

• A new oxidant “X” has been identified which plays a significant role in the formation of gaseous Sulphuric acid in the atmosphere.
• Until now, it was thought that the combination of OH (hydroxyl radical) oxidant with sulphur dioxide (SO{-2}) was responsible for the formation of gaseous sulphuric acid in the atmosphere.
• It is considered to contribute the formation of 50% of the total sulphuric acid produced in the atmosphere. Scientist relate the formation of “X” with “reaction of surface emission, such as naturally produced hydrocarbons, with ozone.”

• A new species of spider was named after the British naturalist and famous TV Broadcaster Sir David Attenborough. The species prethopalpus attenboroughi is found only on Horn island in the Torres Strait in Queensland, Australia.
• The other name of Prethopalpus is goblin spider.
• Earlier a fossil of a fish Materpiscis attenboroughi that existed 380 million years ago was named after Sir David.

As per warnings of NASA, the Earth might face an intense summer heat wave than what it faced b/w 1951 to 1980. Agency reveals that over the past 30 years the northern hemisphere has seen more "hot", "very hot"and “extremely hot” summers (as classified by the agency).
Earth's northern hemisphere, which has 90 % of the planet's land, has become much more susceptible to experience an extreme summer heat wave compared to a base period from 1951 to 1980.