The temperature of the Sun is over 5,000 degrees Fahrenheit at the surface, but it rises to perhaps more than 16 million degrees at the center. The Sun is so much hotter than the Earth that matter can exist only as a gas, except at the core. In the core of the Sun, the pressures are so great against the gases that, despite the high temperature, there may be a small solid core. However, no one really knows, since the center of the Sun can never be directly observed.

Solar astronomers do know that the Sun is divided into five layers or zones. Starting at the outside and going down into the Sun, the zones are the corona, chromosphere, photosphere, convection zone, and finally the core. The first three zones are the regarded as the Sun’s atmosphere. But since the Sun has no solid surface, it is hard to tell where the atmosphere ends and the main body of the Sun begins.

The Sun’s outermost layer begins about 10,000 miles above the visible surface and can be seen during an eclipse (日食) such as the one in February 1979. Other time, the corona can be seen only when special instruments are used on cameras and telescopes to shut out the glare of the Sun’s rays.

The corona is a brilliant, pearly white, filmy light as bright as the full Moon. Its beautiful rays are a sensational sight during an eclipse. The corona’s rays flash out in a brilliant fan. The corona is thickest at the sun’s equator (赤道).

The corona rays are made up of gases streaming outward at tremendous speeds and reaching a temperature of more than 2 million degrees Fahrenheit. The rays of gas thin out as they reach the space around the planets. By the time the Sun’s corona rays reach the Earth, they are weak and invisible.

I believe that animals possess greater intelligence than most people think. But plants? I’ve never considered the possibility of plant intelligence. The idea seems absurd.

Yet I've had friends argue that plant intelligence might exist. “What are the differences between plants and animals?” they ask, and then they argue about certain species that seem to share the intelligence of both plants and animals.

New research suggests that plants communicate via “networks”. Plant communication is not idea, and cannot indicate that it is a kind of intelligence, but it is still interesting.

Recent research from Vidi researcher Josef Stuefer at the Radboud University Nijmegen shows that plants have their own chat systems that they can use to warn each other. Therefore plants are not boring and passive organisms that just stand there waiting to be cut down or eaten up. Many plants form internal communication networks and are able to exchange information networks and are able to exchange information efficiently.

Many herbal plants such as strawberries and clovers (三叶草) naturally form networks.

Individual plants remain connected with each other for a certain period of time by means of runners (plant stems that grow along the ground and put down roots to form new plants). These connections enable the plants to share information with each other via internal channels. They are therefore very similar to computer networks. But what do plants chat to each other about?

Recently Stuefer and his colleagues were the first to prove that clover plants warn each other via the network links if danger is nearby. If one of the plants is attacked by caterpillars (毛虫), the other members of the network are warned via an internal signal. Once warned the intact (完好无损的) plants strengthen their chemical and mechanical (机体的) resistance so that they are less attractive to advancing caterpillars. Thanks to this early warning system, the plants can stay one step ahead of their attackers. The research has shown that this significantly limits the damage to the plants.

Again, I don’t believe this reflects intelligence, but it’s is certainly fascinating.

You may have noticed sudden, brief twitching (抽动) at some point while your dog was sleeping and wondered if he was dreaming or even expressing some type of discomfort.

These involuntary movements only occur during dream states and usually don’t last long. So is twitching just a normal part of dreaming, or are there times when you should worry?

Dogs sleep an average of 12-14 hours each day. While they sleep, a dog’s brain processes information and experiences from the day through dreams. Twitching is often related to active dream cycles in the brain.

According to research by psychologist Stanley Coren, an average-size dog will dream about every 20 minutes, and these dreams will last about a minute. Larger breeds have fewer dreams that last longer—about every 45 minutes for 4 minutes. The opposite is true for smaller breed dogs; they will dream about every 10 minutes for up to 30 seconds.

Dogs experience the same dream stages as humans, including non-rapid eye movement (NREM), short-wave sleep (SWS), and rapid eye movement (REM). During the REM state, a dog’s eyes move around behind their closed eyelids, and the large body muscles are turned off so the dream is not physically acted out. The amount of twitching depends on how much these off switches cramp (阻碍) muscle movement.

If your dog sleeps next to you, he may unintentionally disturb your sleep with his sudden body movements. However, it is often advised not to awaken a dog that is twitching in his sleep unless he is clearly uncomfortable.

A bad dream or night terror could be the cause of these involuntary movements, and they may wake up frightened. Try to avoid touching them so they don’t bite you as a result of being shocked and panicked. Instead, gently call your dog’s name until they respond. Speak calmly and tell them that they are safe and secure after they wake up. While they appear to be pretty active in their sleep, dreaming dogs may be slow to awaken.