Why is venus sometimes called the morning star or the evening star?

Why is Venus called the Morning Star?

Venus, known sometimes as the Brilliant Light of Love, can outshine everything in our view except the Sun and the Moon. But we see it only in the early morning or evening, which is why it is known as both the Morning Star and the Evening Star. The nicknames, commonly applied many years ago by people who had little idea of the true nature of Venus, are misnomers. Venus is not a star but a planet. Like Earth, it orbits the Sun, travelling closer to it than we do on average about three fifths of our distance.

Astronomers can plot Venus’s position by measuring the angle between a line joining the Earth to Venus, and a line from the Earth to the Sun. Because Venus is closer to the Sun than we are, the angle between the Sun and Venus, as seen from Earth, never gets much larger than 45 degrees, an eighth of a circle. If you can see Venus in the eastern sky, daylight for most people will be no more than three hours away. Thus, Venus appears in the early morning and vanishes when the Sun is up. See Venus in the west, the so-called Evening Star, and night is about to fall.

Like the Moon, Venus has phases, which you can see quite clearly if you watch regularly with a good pair of binoculars. It is at its brightest visible often at noon when the angle between the planet and the Sun is 39 degrees. Its crescent then corresponds to that of the Moon five days after a new Moon.

When we see the bright light of Venus, we are in fact not seeing the planet itself but its atmosphere. Venus is completely enshrouded in swirling, unbroken clouds, which reflect 76 per cent of its received sunlight. These clouds, made up almost entirely of carbon dioxide, mask the planet in secrecy, blocking all attempts to view its surface by telescope. But recent advances in radar and space exploration have enabled us to peek through the curtain, and assess the planet’s forbidding environment and cratered terrain.

Because of its similarity in size, slightly smaller than the Earth in diameter, Venus is often referred to as Earth’s twin sister. We now know that size and mass are among the few things they have in common. Because Venus is closer to the Sun, it is logical to expect that it would be warmer there than on Earth. Data sent back by spacecraft show that it is astonishingly warmer. Its average surface temperature is about 460°C (860°F), over four times that of boiling water. Venus has a runaway greenhouse effect, caused by its enormous volume of carbon dioxide more than 7500 times as much as the Earth’s. Atmospheric pressure is almost 100 times as high.

From Earth, Venus can be a beautiful sight, a worthy choice by the Romans when they named it after their goddess of love and beauty. But they didn't know what we know about the planet’s torrid temperament, a hellhole where life is impossible and where even the most intrepid of human explorers may never be able to land.