Moon ............. and Venus - - - Conjunction !!!

 

Seen together ~ Moon and Venus — neighbours only to our eyes!

This evening, 14 September 2026, at Triplicane saw  a slender crescent Moon appeared to almost embrace brilliant Venus in the western sky. They are separated by an enormous distance in space; yet, viewed from Earth, their orbital paths briefly brought them into the same small patch of our sky — a lovely celestial conjunction.

Venus is one of the most fascinating planets because, in some ways, it is Earth’s near-twin — and in other ways, it is almost the opposite of Earth.  Venus is the second planet from the Sun. It is almost the same size as Earth: its diameter is about 12,100 km, only a little smaller than Earth’s 12,742 km. It is a rocky planet with a metal-rich interior, mantle and crust, and it probably formed around 4.5 billion years ago from the same rotating disc of gas, dust and rocky material that produced the Sun and the other planets. In the early Solar System, countless small rocky bodies collided and gradually accreted into larger worlds; Venus was one of those worlds.

What makes Venus especially interesting is what happened afterwards. It may once have had far more water than it has today, perhaps even conditions much less hostile than the present planet. But Venus is closer to the Sun, and over immense periods its atmosphere became dominated by carbon dioxide. This produced an extreme greenhouse effect. Today its surface temperature is around 465°C — hot enough to melt lead — and the atmospheric pressure at the surface is about 90 times that of Earth. Its clouds are largely made of sulphuric-acid droplets.

Yet from Earth Venus looks serene and beautiful. Its thick clouds reflect sunlight extremely efficiently, which is why it becomes the brightest “star-like” object in our sky after the Sun and Moon. The “Evening Star” you photographed is therefore actually a fiercely hot, cloud-covered planet.

One extraordinary fact about Venus is its rotation. It turns very slowly and backwards compared with most planets. One rotation takes about 243 Earth days, while Venus goes around the Sun in about 225 Earth days. So, remarkably, a Venusian day is longer than a Venusian year.  It sounds strange because we use “day” and “year” casually.

On Venus:

• One year = the time Venus takes to go once around the Sun: about 225 Earth days.
• One rotation day = the time Venus takes to turn once on its own axis: about 243 Earth days.

So Venus completes an entire orbit around the Sun before it has finished one full rotation on its axis. And because it rotates in the opposite direction, the Sun would appear to rise in the west and set in the east.

There  are two photos one taken with Nikon d7500 / 300mm lens and then cropped and another taken casually with Pixel Pro 8 phone.    Venus, like the Moon, shows phases — crescent, half, gibbous and nearly full — because it orbits closer to the Sun than Earth does. Galileo’s observation of these phases in the early 1600s became powerful evidence that Venus goes around the Sun rather than around Earth.

If you wonder where are they :  The Moon is much, much closer to Earth than Venus.

• Moon: on average about 384,400 km from Earth. Its distance varies roughly from 363,000 km to 405,000 km because its orbit is not perfectly circular.
• Venus: its distance from Earth changes enormously. At its closest it can be about 38 million km away; at the far side of the Sun it can be around 260 million km away.

So even when the Moon and Venus look almost side-by-side in   photograph, Venus is actually tens to hundreds of times farther away.  For perspective, light takes only about 1.3 seconds to travel from the Moon to Earth, whereas light from Venus can take roughly 2 to 15 minutes, depending on where Venus is in its orbit.

For a casual observer the photo with Pixel may sound better but actually it is not – Nikon has given an astronomical picture.  The processed Pixel picture has become a little more “illustrative” than what I actually saw.  The original Pixel photograph is actually valuable precisely because it records the real Chennai rooftops, clouds and sky.   

               Nikon frame is the better astronomical photograph because the Moon and Venus are cleaner, more delicate, and more naturally rendered. The Pixel photograph is the better scene-setting photograph because it shows the conjunction in the real urban night sky above the rooftops. The clouds and buildings give it context and atmosphere.The weakness of the Pixel image is that the phone’s night processing has made the crescent rather bright and slightly bloomed, and Venus has become a small starburst instead of a clean point. That  faint remainder of the Moon's globe is visible inside the crescent in Pixel photo  is earthshine — sunlight reflected from Earth onto the Moon's night side and then reflected back to us.

One would be inclined to say ‘Moon – Venus” conjunction over Chennai night sky – both much closer but that apparent closeness is what astronomers call a conjunction. They are emphatically not physically close: the Moon is only a few hundred thousand kilometres from Earth, whereas Venus is many tens or hundreds of millions of kilometres away depending on where it is in its orbit. What is  photographed and seen here therefore is  a beautiful perspective alignment — rather like seeing two distant objects apparently side-by-side although one is vastly farther away.

Interesting !

Regards – S Sampathkumar

14.9.2026