1) The term "bull market" refers to a period of rising stock prices, while a "bear market" refers to a period of falling stock prices.

2) The first photograph of a black hole was captured in 2019 using a network of telescopes around the world.

3) In response to the global push for sustainability, many countries have set ambitious goals for transitioning to renewable energy sources, such as the aim to achieve carbon neutrality or significant reductions in greenhouse gas emissions by specific target years.

4) The world's oldest tree is believed to be a bristlecone pine named "Methuselah" in California, estimated to be over 4,800 years old.