Frequently asked questions about space and exploration
Short answers to the questions that come up most often. Each one links to the article with the full explanation.
About the site
Is Frontier Academy a school?
No. It is a free educational website, not a school, and it has no connection with any school, academy or trust with a similar name. The articles are written for pupils aged about 10 to 15 and for the teachers and parents who help them. See Start here for suggested reading orders, or About for who runs the site.
Can I use the articles in lessons?
Yes. You are welcome to show an article on the board, set it as homework reading, or use the worked examples and activities as starters and plenaries. The Free materials page has observation tables, checklists and practice questions written out ready to copy.
Why do some numbers differ from my textbook?
Most figures here are rounded, so you may see 150 million km where a textbook gives 149.6 million km. Some numbers also change as scientists learn more: the count of known moons around Jupiter and Saturn has risen many times, which is why our planets table gives minimums. An older textbook may have been right when it was printed.
Space
Why does the Moon change shape?
It does not. The Sun always lights half of the Moon, and as the Moon orbits the Earth, about once every 29.5 days, we see different amounts of that lit half. See the phases of the Moon.
Is it hotter in summer because the Earth is closer to the Sun?
No. The Earth is closest to the Sun in early January, during the northern winter. Seasons are caused by the 23.4° tilt of the Earth's axis: when your hemisphere leans towards the Sun, the Sun climbs higher, its light is more concentrated and days are longer. See seasons, eclipses and tides.
Why isn't there an eclipse every month?
The Moon's orbit is tilted by about 5° to the Earth's. Most months, the new and full moons pass slightly above or below the line joining the Sun and Earth, so the shadows miss. Eclipses happen only when a new or full moon falls near the points where the two orbits cross.
Can I look at the Sun during an eclipse?
Never look directly at the Sun, during an eclipse or at any other time, and never through binoculars, a telescope or a camera viewfinder. Even a thin crescent can permanently damage your eyes, without any pain at the time, and sunglasses do not protect you. Use a pinhole projector, or eclipse glasses that meet the ISO 12312-2 safety standard, with an adult present.
Why is Pluto no longer a planet?
In 2006 the International Astronomical Union defined a planet as a body that orbits the Sun, is round because of its own gravity, and has cleared the neighbourhood of its orbit. Pluto fails the third test, because it shares the Kuiper Belt with many other icy bodies, so it is now a dwarf planet.
Is there gravity on the International Space Station?
Yes, about 90% as strong as on the ground. Astronauts float because they and the station are in free fall, moving sideways so fast (about 28,000 km/h) that the Earth's surface curves away as quickly as they fall. See the International Space Station and how rockets work.
The Earth and exploration
Why was longitude so much harder to find than latitude?
Latitude can be read from the sky: the height of Polaris, or of the Sun at noon, tells you how far north or south you are. Longitude depends on time. The Earth turns 15° an hour, so comparing local time with the time at Greenwich gives your longitude, but that needs a clock that stays accurate for months at sea. John Harrison's marine timekeepers showed it could be done in the 1700s. See latitude and longitude.
Did Magellan sail around the world?
Not personally. Ferdinand Magellan led the expedition that left Spain in 1519, but he was killed in the Philippines in 1521. The Victoria, under Juan Sebastián Elcano, completed the voyage in September 1522 with 18 men on board. See the Magellan–Elcano expedition.
Why did Amundsen reach the South Pole before Scott?
Historians usually point to several reasons together: Amundsen's dog teams and expert skiers suited the snow, his expedition had a single goal, and Scott's party relied on ponies and motor sledges that failed, then on pulling sledges by hand. Amundsen arrived on 14 December 1911, Scott on 17 January 1912. See the race to the South Pole.