Mercury has been known to humanity since ancient times and although its discovery date is unknown, the first mentions of the planet are believed to be around 3000 BC by the Sumerians.
A year in Mercury is 88 days, yet a Mercury day is 176 Earth days. Mercury is nearly tidally locked to the Sun – also known as a gravitational lock – and over time this has slowed the rotation of the planet to almost match its orbit around the Sun.
Mercury orbits so quickly around the Sun that early civilizations believed it was actually two different stars – one which appeared in the morning and another which appeared in the evening.
Mercury is the smallest planet in the solar system with a diameter of 4,879 km and is one of five planets that is visible to the naked eye.
FACTS ABOUT VENUS
Venus is the second brightest natural object in the sky. The planet has an apparent magnitude of -3.8 to -4.6, which makes it visible on a bright, clear day. The Moon is the only other natural object that is brighter.
Venus is sometimes referred to as the “morning star” and “evening star”. This dates back to ancient civilizations who believed that Venus was in fact two distinct stars appearing in the sky. When the orbit of Venus overtakes Earth’s orbit, it changes from being visible at sunrise to being visible at sunset. They were known as Phosphorus and Hesperus by the Greeks, and Lucifer and Vesper by the Romans.
One day on Venus is longer than one year. Due to the slow rotation on its axis, it takes 243 Earth-days to complete one rotation. The orbit of the planet takes 225 Earth-days – making a year on Venus shorter on day on Venus.
Venus is named after the Roman goddess of love and beauty. This may be, in part, due the brightness of the planet and may date back to the Babylonians in 1581 who referred to Venus as “bright queen of the sky”.
Venus is sometimes called Earth’s sister planet. This is because their size is very similar (there is only a 638 km different in diameter) and Venus has around 81% of Earth’s mass. They are also similarly located with Venus being the closest planet to Earth. Both planets also have a central core, a molten mantle and a crust.
FACTS ABOUT EARTH
The Earth was once believed to be the centre of the universe. For 2000 years ancient astronomers believed that the Earth was static and had other celestial bodies travelling in circular orbits around it. They believed this because of the apparent movement on the Sun and planets in relation to their viewpoint. In 1543, Copernicus published his Sun-centered model of the Solar System which put the Sun at the centre of our solar system.
Earth is the only planet not named for a mythological god or goddess. The other seven planets in the solar system were named after Roman gods or goddesses. For the five visible to the naked eye, Mercury, Venus, Mars, Jupiter and Saturn they we named during ancient times. This Roman method was also used after the discovery of Uranus and Neptune. The word “Earth” comes from the Old English word “ertha” meaning ground or land.
Earth is the most dense planet in the solar system. The density of Earth differs in each part of the planet – the core, for example, is denser than the Earth’s crust – but the average density of the planet is around 5.52 grams per cubic centimetre.
The gravity between the Earth and the Moon causes the tides on Earth. This effect on the Moon means it is tidally locked to Earth – its rotation period is the same as its orbit time so it always presents the same face to Earth.
The rotation of the Earth is gradually slowing down. The deceleration of the Earth’s rotation is very slow, approximately 17 milliseconds per hundred years. Eventually this will lengthen our days but it will take around 140 million years before our day will have increased from 24 to 25 hours.
FACTS ABOUT MARS
Mars is the fourth planet from the Sun and last of the terrestrial planets and is around 227,940,000 km from the Sun.
The planet is named after Mars, the Roman god of war. It was known to the ancient Greeks as Ares, their god of war. This is thought to be because of the blood-red color of the planet which was also used by other ancient cultures. Chinese astronomers call Mars the “fire star” while ancient Egyptian priests called it “Her Desher” meaning “the red one”.
The landmass of Mars and Earth is very similar. Despite Mars being just 15% the volume and 10% the mass of Earth, it actually has a similar landmass because water covers about 70% of Earth’s surface. The surface gravity of Mars is about 37% the gravity found on Earth. This means that on Mars you could in theory jump 3x higher than you could on Earth.
Only 16 of the 39 Mars missions have been successful. Beginning with the USSR’s Marsnik 1 which was launched in 1960, 39 orbiters, landers and rovers have been to Mars but only 16 of those missions were a success. In 2016, Europe’s Exobiology on Mars program will search the planet for signs of Martian life as well as study the surface and terrain of the planet and map potential environmental hazards to future manned missions to Mars.
Pieces of Mars have been found on Earth. It is believed that trace amounts of the Martian atmosphere were within meteorites that the planet ejected. These meteorites then orbited the solar system for millions of years amongst the other objects and solar debris before eventually entering the Earth’s atmosphere and crashing to the ground. The study of this material has allowed scientists to discover more about Mars before launching space missions.
Teori Laurasia-Gondwana Eduard Zuess dalam bukunya The Face of the Earth (1884) dan Frank B. Taylor (1910) mengemukakan teorinya bahwa pada mulanya terdapat dua benua di kedua kutub bumi. Benua-benua tersebut diberi nama Laurentia (Laurasia) dan Gondwana . Kedua benua itu kemudian bergerak secara perlahan ke arah ekuator sehingga terpecah-pecah membentuk benua-benua seperti sekarang. Amerika Selatan, Afrika, dan Australia dahulu menyatu dalam Gondwanaland, sedangkan benua- benua lainnya menyatu dalam Laurasia. Teori Laurasia-Gondwana diyakini oleh banyak ahli karena bentuk pecahan-pecahan benua tersebut apabila digabungkan dapat tersambung dengan tepat. Namun, penyebab pecahnya benua-benua tersebut belum dapat ditemukan. Teori konveksi Teori konveksi mengemukakan bahwa terjadi aliran konveksi ke arah vertikal di dalam lapisan astenosfer yang agak kental. Aliran tersebut berpengaruh sampai ke kerak bumi yang ada di atasnya. Aliran konveksi yang merambat ke dala
Bentuk permukaan Bumi terdiri atas daratan dan juga samudera atau macam-macam laut . Bentuk daratan yang ada di Bumi tergambar dalam bentuk pulau. Pulau- pulau yang berdekatan dalam jumlah besar membentuk sebuah benua. Ada enam benua di dunia , dan salah satu diantaranya tidak dihuni oleh manusia karena terletak di kutub selatan Bumi dan berupa es abadi. Bentuk dan letak benua tampaknya adalah statis atau tetap. Namun tahukah Anda bahwa benua ini bergerak, meskipun tidak terlihat atau terasa secara langsung tapi benua ini bergerak perlahan- lahan. Hal ini dipelajari dalam suatu teori mengenai benua. Salah satu teori tentang benua yang dikenal adalah Teori Apungan Benua. Mengenai teori ini kita akan membahas dalam artikel ini secara lebih lengkap Teori apung benua atau Pangea merupakan sebuah teori yang menyatakan bahwa jutaan tahun silam, Bumi ini hanya memiliki satu ekosistem darat yang sangat besar yang disebut dengan Pangea. Lalu karena alasan tertentu yang belum diketahui
facts of universe The Universe Is Getting Bigger NASA, ESA, E. Jullo (JPL/LAM), P. Natarajan (Yale) and J-P. Kneib (LAM) The Universe's Growth Spurt Is Accelerating In the 1920s, astronomer Edwin Hubble made the revolutionary discovery that the universe is not static, but rather is expanding. But, it was long thought that the gravity of matter in the universe would slow this expansion or even cause it to contract. In 1998, the Hubble Space Telescope studied very distant supernovas and found that, a long time ago, the universe was expanding more slowly than it is today. This puzzling discovery suggested that an inexplicable force, called dark energy, is driving the accelerating expansion of the universe. [ Full Story ] While dark energy is thought to be the strange force that is pulling the cosmos apart at ever-increasing speeds, it remains one of the greatest mysteries in science because its detection remains elusive to scientists. NASA, ESA, the Hub
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