Sunday marked the the first official day of summer in the Southern Hemisphere, where Skipper Wilson and his fellow sailors are making their way east. Solstices occur twice each year — once in June and once in December. In the Northern Hemisphere, the winter solstice was celebrated with snow falling across the United States and Canada. For those of us north of the equator, we’re now officially in winter. For those people, like Skipper Wilson, who are south of the equator, they’ve moved into the summer months.

Two things cause seasons. The first is that the Earth revolves around the sun. The second is that the Earth is tilted on its axis. (Imagine a ball with a stick pushed through its middle. If the Earth is the ball and the stick represents the North and South Poles, then the stick isn’t straight up and down, but leans over at an angle.)

The solstice marks the extremes of light that the Earth receives. On December 21, the Northern Hemisphere was tilted the furthest from the sun that it gets all year. That means that you didn’t get a lot of daylight and instead had a very long night. The Southern Hemisphere, however, was tilted closest to the sun so it had many hours of daylight.

When you’re sailing, it’s good to have lots of hours of daylight because it’s easier to be able to see what’s going on around you. You can read here what Skipper Wilson has been up to since the longest day of the year in the Southern Hemisphere.

The closest land mass to most of the fleet of sailboats is currently Australia, the sixth largest country — and the smallest continent — in the world. Australia is what the United Nations calls a megadiverse country. Home to many unique creatures, megadiverse countries are the 17 nations that contain the majority of the world’s species. Australia, for instance, is one of the only places where kangaroos and koalas (both of which are marsupials — mammals that have a pouch to protect their young after birth), emus, and platypus are found in the wild.

Australia is also known for its Great Barrier Reef, which is the largest coral reef system in the world. Coral is a tiny, shell-like creature that grows on the skeletons of previous corals. Over the years, these creatures create what is known as a reef, which is a mostly stationary feature not too far under the surface of the water. Reefs provide food and shelter for many different types of plants and animals, making them very important to take care of.

The Great Barrier Reef, because of its size, offers a home to thousands of species. Unfortunately, it’s very fragile and can be easily damaged by global warming, pollution, and too much interaction with humans. Some of the animals and plants the reef protect are also endangered. The Great Barrier Reef is beautiful but delicate, and it would be easy for humans, even without trying, to interrupt the food chain and the flow of life that depends on it.

We at Science NetLinks would like to join all the sailors and Vendée Globe watchers in wishing a speedy recovery to Skipper Yann Eliès. Skipper Eliès fell on his boat last week and broke his leg. A ship from Australia was sent out to meet his boat, the Générali, and evacuate him back to land. He’s now at the hospital where he’ll have surgery to fix his leg.

You can read Skipper Wilson’s latest log here.

If you’ve been checking in with Skipper Wilson over on sitesALIVE!, you know that the storms predicted for last week brought very strong winds with them. How much wind are we talking about, though?

Wind speed is measured on what’s called a Beaufort Scale. This is what you might experience if you were in a place with different speeds of wind:

You can see some of the storm footage in this video from Skipper Wilson. Unless you speak French, you probably won’t understand much of what he’s saying, but it does give you a sense of the huge waves and strong winds he’s been encountering this week.

Skipper Wilson is still heading east, but the winds ended the race for a number of his fellow sailors. Two of them had their masts snap off, a couple boats had rudders break, and a few had other mechanical problems. Luckily, all the skippers are fine and are headed back to land. Nineteen of the original thirty boats that began the race last month are still competing.

You can read Skipper Wilson’s latest log here.

Skipper Wilson is expecting to sail into a storm sometime in the next day or so. He has been on a boat during storms before, so he knows that although the strong winds and big waves can be scary, he should come through it all okay. (When someone talks about “weathering a storm,” this is exactly where the phrase came from.)

The boat’s long keel (that you saw in this post) is designed for rough weather and helps to keep the boat upright. And Skipper Wilson’s computers give him an advantage that sailors didn’t have a hundred years ago: He’s able to find out almost immediately when the storm shifts. Meteorologists (weather men and women) examine information from satellites and from buoys and from the sailors themselves and can give pretty good estimates of what the storm is going to do next. In the olden days sailors relied on traditional records of where storms moved in the oceans and on the weather that they could see from the ship to guess what was happening around them. Today’s computers give a much more accurate view, offering Skipper Wilson more options.

Listen to Skipper Wilson talk about the coming storm here. You can also read his most recent thoughts on the storm here.

Skipper Wilson is a month into his trip. Before he left, he had to figure out what he was going to eat for the next four months. After all, because he can’t stop, he had to take everything with him. His mom helped him come up with some menus and he worked with professionals to come up with foods that had lots of vitamins and minerals to keep his body healthy. (In the olden days, for instance, lots of sailors died of scurvy, an illness that comes from a lack of Vitamin C found in food like oranges, carrots, and broccoli. People now know to make sure they eat fresh fruit and vegetables or to take a multivitamin if they can’t to avoid the problem.) Skipper Wilson also worked hard to stock food that would give him lots of energy without taking up a lot of space.

Food has energy stored in it in the form of calories. When you eat, the energy is transfered to your body. Your body has two ways to deal with the energy. One is to use it up. You might use energy playing during gym class or running during recess. Skipper Wilson uses it up hoisting sails and working on the Great American III. Your body even uses a certain amount of energy just breathing and thinking.

The other thing the body can do with energy is to store it. The human body has evolved to protect it from starvation. On days when the body doesn’t use the energy it takes in, it stores it in fat cells. When humans used to have to go out and find food in the wild, there would have been less to eat in the winter. The body could then convert some of the energy it had stored in the fat cells to keep the body alive and in working order.

One of the reasons people gain weight is because they take in a lot more calories than they use up. Because food can be easily found today, it’s rare that the body needs to store energy for harder times. But if a person doesn’t do enough activity to use up the energy in the food he or she has eaten, the body has no choice but to store the excess in its fat cells.

Skipper Wilson works very hard on the boat and he is awake a lot of the time, which means he needs a lot of energy. You can read about what he and his team figured he would use up in this Question and Answer session here.

You also can see photos of some of Skipper Wilson’s food supplies here and how he rations it out to last for the whole journey.

Unlike the world’s continents, which are divided up into countries with borders and governments that keep each one separate, the oceans lack physical boundaries. This can be good, because you don’t need a passport to travel from the Pacific to the Atlantic. On the other hand, though, pollution doesn’t get stopped at the border either.

Nearly 71% of the earth’s surface is covered by oceans. That means that things that end up in the water (accidentally or on purpose) can travel a long way unless they’re fished out by someone or something. Things like oil spills show how quickly and how far the ocean can carry pollutants that can sicken or kill fish, birds, and sea mammals. It’s not just those creatures living in the ocean who are affected. People who eat plants or animals that come from the ocean can get sick, too, if they eat something that’s been contaminated.

Tossing trash into the ocean itself isn’t the only problem. Pollution in fresh water and in the air affects the oceans too. Dumping into streams and rivers, even hundreds of miles from the ocean, takes materials downstream with the current, often washing them out to sea. The water cycle means that water from all over evaporates, joins up with particles in the air, and returns to earth elsewhere through rain and other precipitation. Pollution released into the air can end up affecting the oceans that way, too.

Pollution travels and hurts the whole ocean. But because the oceans don’t belong to any one nation, all countries must work together to help clean them up and to keep them pollution-free. There are international laws that work to do that, but everyday people can do their part too, by making sure they don’t pollute where they live.

Skipper Wilson writes about some of the ways he and his competitors are trying to keep the oceans clean.

Skipper Wilson had a noisy night yesterday. Around midnight, the boat started making a new noise—an unexpected one. The sound resembled a high-pitched vibration, maybe similar to a mixer on its highest setting.

Skipper Wilson and his boat repair person in Maine talked on the telephone and they think that the sound may have been caused by a piece of the fairing breaking off. The fairing is a covering placed on the bottom of the boat to help the water move around the hinge that attaches the keel to the hull. In the picture to the right, you can see the hull (the raft-like portion of the boat) of the Great American III. The keel is the big orange part sticking out under the hull. On Open 60s, the keel is particularly long to help the boat stay upright. The two fairings are half-cone-shaped pieces that go around the keel in front and in back where it attaches to the hull. You can also get an idea of the different parts of the hull by looking here.

The fairing isn’t a necessary part of the boat, so it’s not a big deal if parts of it come off. Noises are always important to investigate, though, because they could be a sign of something wrong.

Listen to Skipper Wilson’s latest podcast and read today’s log.

Yesterday, Skipper Wilson crossed the equator. He’s now sailing in the Southern Hemisphere.

Skipper Wilson shares some of the traditions of crossing the equator here. Writer Dava Sobel, author of Longitude, also shares some thoughts about the equator, as well as about latitude and longitude, the two ways we have of measuring location on a map.

You also can listen to Skipper Wilson as he talks about approaching the equator, and watch the crossing on this video:

In a recent post and podcast, Skipper Wilson talked about getting through the Doldrums. What are the Doldrums exactly?

The Doldrums are the area of the Atlantic and Pacific Oceans near the equator. They stretch roughly from 5° north of the equator to 5° south of it and are sometimes known as the Intertropical Convergence Zone. They aren’t in a fixed location, though, because they are affected by a number of things, including the season, the sun, and the open sea.

The area at the equator gets a lot of sun exposure, which heats both the air and the water. In this low-pressure zone, the air is hot and moist and rises up into the atmosphere through evaporation. If the air is rising, it’s not blowing across the surface of the water. This can be bad for a sailor, who needs horizontal air flow (wind) to fill his or her sails. Back in the 16th century, English traders periodically got caught in this windless area, and it’s they who gave the Doldrums such a descriptive name. (If you’re in the doldrums, you lack the energy and spirit to get yourself moving.)

However, the Doldrums also are where the trade winds from the Northern Hemisphere and the Southern Hemisphere meet. When these winds meet, expect sudden and strong wind and rain storms. Combine that with very warm temperatures in the late summer, and hurricanes can form.

The Doldrums are unpredictable because there are these two very different situations playing out at the same time: calm weather and sudden storms. It can be very frustrating to sail through this region, so it’s good to hear that Skipper Wilson thinks he’s finally through them.

What do you see when you look up at the night sky: The moon? Stars? Constellations?

Constellations are groupings of stars that, over many thousands of years, people have drawn imaginary lines between to represent a picture. It was their way of making sense of what they saw in the night sky. People have named 88 different constellations. If you know where to find a certain constellation at a certain time of the year, you can tell what direction you’re facing. That can be particularly handy when you’re sailing on the open ocean.

Which constellations appear in your night sky? The answer depends a lot on where you live.

If you live in the Northern Hemisphere, you only see some stars and certain constellations. Once you cross the Equator, some of those stars become difficult to see. But those of you in the Southern Hemisphere get other stars and constellations to look at instead. In the north, two of the best known star groupings are the Big and Little Dippers. (The star at the tip of the Little Dipper is Polaris — also called the North Star — and can always be found in the northern part of the sky.) In the south, the best known constellation is the Southern Cross.

Listen to Skipper Wilson’s most recent podcast to hear about the stars he can see and what constellations he’ll be looking for when he crosses the Equator.