You might have seen beautiful rainbows in the sky before. They form when sunlight falls on water drops in the air. But in fact, moonlight can also create rainbows in the same way. They are called “moonbows”. They are similar to rainbows, but they are created by moonlight instead of direct sunlight.

Moonbows are more unusual than rainbows. Different weather and astronomical conditions have to be just right for moonbows to be created. The moon has to be very low in the sky—only 42 degrees from the horizon(地平线). The moon period has to be a full moon or nearly full. The sky must be very dark for a moonbow to be watched clearly—any bright light can obscure it. Water drops must appear in the air in the opposite direction of the moon. Moonbows appear on the opposite side of the moon and usually look white to the human eye. This is because their colors are not bright enough to be noticed by the human eye.

Moonbows more often appear in some locations around the world. Most of these locations usually have waterfalls, which create thin fog in the air. Some of these locations are the Yosemite National Park in California and Cumberland Falls State Resort Park in Kentucky and Waimea in Hawaii, US.

Moonbows do really happen. So at a certain time and a certain place, when a moonbow happens to appear, you can’t miss it if you’re right there.

In Singapore, it takes many middle school students a lot of time to study. People think good schooling is the key to success in their future. So, many of these students try their best to get good grades in their tests (考试). They have a lot of homework every day and tests are usually difficult. Sometimes, some of them have to go to remedial classes after school.

There are many after-school activities: sports and games, music and dance, hiking and rock-climbing, etc. They are also very happy to do community service (社区服务).

In their free time, most students like to listen to pop music. Hollywood, Hong Kong and Singapore movies are very popular among them. Quite a few of them also use their free time to surf the Internet, email their friends and play computer games.

They sometimes go to cafes, fast food restaurants, shopping centers and big bookstores.

So, it looks like the life as a middle school student in Singapore is not easy but it is rich and colorful.

On July 23rd, China successfully sent its first Mars probe by Long March-5 Y4 rocket into the scheduled orbit. 2020 is regarded as the year of Mars as three spaceships are on a 505-million-kilometer journey to Mars. China, the US and the UAE（阿联酋）have all sent their probes to the red planet.

Timing is everything. Every 26 months, the window of the opportunity opens. During that time, the Sun, the Earth and the Mars are in line, and the earth stays in the middle. The distance between Mars and the Earth can be the shortest. That means the journey will take six or seven months instead of the usual nine months. The window of opportunity began on July 15, 2020 and ended on August 15, 2020.

To make a soft landing on Mars has never been an easy job. Besides the long travel distance, scientists think one of the biggest challenges is the seven minutes of terror（恐怖七分钟）. That is, the probe needs to reduce the speed from 20, 000 kilometers ever hour to zero in seven minutes to land on the Mars. The atmosphere（大气层）of Mars is very thin. It could not provide enough help for the landing. What’s worse, there are a lot of sandstorms on Mars, making the landing much more difficult.

Anyway, scientists are trying hard to solve the mystery of life on Mars: Is there, or was there ever, life on Mars?