The Sun Temple of Modhera was built in 11th century AD during the reign of Solanki ruler Bhimadeva-1. This temple is located in Bechraji taluka of Mehsana district of Gujarat, India. The main entrance of the temple faces East and is approached through a water tank which has a series of steps on all four sides. This step well has 108 small temples of various Hindu deities. The inner and outer walls of the temple structure is decorated with intricate stone sculptures of deities, dancing Apsaras, musicians, stories from Ramayan and Mahabharat. Nothing is better than a visit during sunrise when the Sun God blesses the temple with his first golden rays!
Rani Ki Vav was built in 11th century AD by Rani Udaymati, the Queen of Bhimadeva-1. It is located about 40 kms north of Modhera in Patan, Gujarat. This magnificent link to our history was buried for centuries and was excavated only in 1960. This is a treasure of beautiful carvings and step wells spread over a huge structure which is 64 mts long, 20 mts wide and 27 mts deep. In 2014, UNESCO declared it as a World Heritage Monument. It is indeed the Queen of step wells in India!
Gandikota is a village in Andhra Pradesh, India. It is situated on the banks of the Penna river that flows through the rocky terrain resulting in the formation of Gorge (‘Gandi’ in Telugu language), which gives a pleasant touch to the place specially during sunrise and sunset. Gandikota also has ruins of a fort with two ancient temples – Madhavaraya Swamy Temple and Raghunatha Swamy Temple and a mosque – Juma Masjid.
Belum caves and Lepakshi complement Gandikota with their own charm. Belum caves is a labyrinth with limestone and stalagmite structures formed due to water flowing underground over thousands of years. From the main entrance, it is about 50m deep and 3.3 Kms long, making it the second longest underground cave in the Indian subcontinent. Lepakshi is another village famous for Veerabhadra temple, an architectural marvel.
December 26, 2019 was marked on my calendar for a long time. Sun, Moon and Earth were scheduled to bring an end to 2019 with the majestic Annular Solar Eclipse. At the peak of the eclipse, the moon covers about 98% of the Sun disk with the outer Sun rim visible from Earth. This phenomenon appears like a ring and is known as the ‘Ring of Fire’.
I was in Kannur, Kerala in Southern India to witness this rare celestial event. A composite picture with key phases of the eclipse is presented here.
As the eclipse created its magic, my heart whispered to the Sun…
ए आफताब! हम तो कायल थे तेरे जोश-ए-नूर के लेकिन, हमने तुझे भी मोहब्बत-ए-महताब के आगोश में देखा है
Translation: Oh Sun! I was in awe of your power but, I can see even you in love with the Moon
Every year from January to May, some very special guests visit Mumbai….Flamingos! These are remarkable birds that flock around the bay area of the city. Mumbai is always-on-the-run busy city but it takes time-off to be charmed by their flamboyance. I had the pleasure to be with them at the Seawoods creek in Nerul. Click on any picture and enjoy the photo gallery !
I started shooting star trails last year and observed that their pattern varies depending on the direction in which the camera is focused. The curiosity to understand the star trails led me to an interesting phenomenon – the Celestial Equator. Hence, during the trek to Singalila Ridge (near Darjeeling, India) in Oct’18, my key objective was to record the Celestial Equator in my pictures.
Firstly, let me answer the most common question asked, “Can we see the star trails?”
Answer is No! Human eye is very powerful but cannot record a scene while a camera can do so on a photo film or digital sensor. As per my settings, a star trail picture is a composite image of minimum 60 frames where each frame has a time exposure of 30 secs. All such frames are shot continuously without disturbing the camera position and settings. Each frame captures the apparent movement of a star due to Earth’s rotation in 30 secs. Individual frames are then stitched together in a photo processing software in ascending order of time sequence to build a single star trail image.
Let’s now take a magnetic compass and explore the night sky….
A) Focus on the North direction as shown by the compass
Earthlings in the Northern Hemisphere are lucky to have a clearly visible star Polaris or North Star about 323 light-years away from Earth. The position of North Star in the sky is aligned with Northern end of Earth’s axis of rotation. It means if the observer is standing at the North Pole, North Star will be seen in the sky vertically above the observer’s head i.e. at the ‘Zenith’.
Now, imagine our observer standing at the North Pole (Latitude = 90 degrees North) starts walking downwards towards the Equator (Latitude = 0 degree). As he moves away from the North Pole, he will see that the North Star is now not visible at Zenith above his head. It actually has shifted down the Zenith towards the horizon.
How much will be the displacement of North Star’s position in sky?
For every 1 degree of latitude walk from North Pole to Equator, North Star will be visually displaced by 1 degree away from the Zenith of the observer’s location and towards the Northern horizon. From the observer’s location, North Star’s position in the sky will be as follows:
From the Zenith = Number of Latitude degrees observer is away from the North Pole or From the Zenith = 90 – Latitude of the observer’s location
From the Horizon = 90 – number of Latitude degrees observer is away from the North Pole or From the Horizon = Latitude of the observer’s location
When the observer reaches Kalapokhri (my location at Latitude = 27 degrees North of Equator) on India-Nepal border then North Star will appear:
From the Zenith = 90 – Latitude of the observer’s location = 90 – 27 = 63 degrees (angle between Zenith→Observer→North Star)
From the horizon = Latitude of the observer’s location = 27 degrees (angle between Horizon→Observer→North Star)
Ok! So, we have identified the angle of view for North Star. Now, let’s check the star trails in the North sky.
Earth rotates from West to East around its axis which is aligned from North Pole to South Pole. Also, North Star is visible at the Zenith of the North Pole. Thus, due to Earth’s rotation, stars in Northern Hemisphere appear to wheel around the North Star in anti-clockwise motion. This makes the North Star as the centre of circular star trails. North Star appears to be stationary because it is aligned along the rotational axis (North-South) of Earth. It implies that irrespective of the observer’s location on Earth, if the North Star is visible then its position indicates the North direction. This is the reason why North Star is so important for navigation.
At the Equator (Latitude = 0 degree), the angle between Horizon→Observer→North Star = 0 degree. Thus, North Star will not be visible. The star trails will appear like semi-circles centred around the position at the horizon below which lies the North Star.
At the North Pole (Latitude = 90 degrees North), the angle between Horizon→Observer→North Star = 90 degrees. Thus, North Star will be visible overhead at the Zenith. The star trails will appear overhead as circles centred around the North Star and parallel to the horizon. Anywhere in the Southern Hemisphere, North Star will not be visible as it will be below the horizon.
B) Focus on the South direction as shown by the compass
As explained for Northern Hemisphere, all stars in Southern Hemisphere also appear to move around South Pole but in clockwise motion. There is an equivalent to North Star known as Polaris Australis but it is barely visible.
In the above picture, you can see that centre of concentric circular star trails is not visible and appears to be at the far-left bottom of the frame. That’s because Sandakphu is in the Northern Hemisphere and South Pole is below the horizon. Now, if we focus towards East or West there should be vertical star trails. Yes, but the magnitude and the angle of vertical trails again will depend on the location of the observer. This brings us to the Celestial Equator!
C) Focus on the West direction as shown by the compass. It should be real geographical West and not the point on West horizon where the Sun sets!
Assume that the observer is standing on the Equator with his arms stretched sideways from left to right and parallel to the ground. If he moves his hand to meet at the top of his head, it results in a semi-circular trajectory. Let’s extend this trajectory up in the sky. This imaginary circular trajectory with an infinite radius in the sky, parallel to the Equator from East horizon to Zenith to West horizon is the Celestial Equator.
The Celestial Equator divides the visible sky anywhere on Earth into Northern and Southern Hemispheres. Thus, at the Equator, one half of the sky towards North of Equator is Northern Hemisphere and the other half of the sky towards South of Equator is Southern Hemisphere. This division of the sky in two equal parts will occur only at the Equator.
What about the other locations on Earth?
To find the answer, let’s ask our observer to face South and walk backwards towards the North Pole. For every 1 degree of latitude walk from Equator to North Pole, the imaginary line dividing the sky called as the Celestial Equator will fall by 1 degree from Zenith towards Southern horizon. This fall is because of the spherical shape of Earth. The portion of the sky North of Celestial Equator will be in Northern Hemisphere and that to the South of Celestial Equator will be in Southern Hemisphere.
Star trails in the Northern Hemisphere will be concentric with the North Star aligned with North Pole and the stars in the Southern Hemisphere will be concentric with the Polaris Australis aligned with South Pole. All stars at or near the Celestial Equator will appear to be moving in almost straight trajectories parallel to the Celestial Equator.
The Celestial Equator will intersect the horizon exactly at the geographical East and West points for the given location. Let’s take the West intersection point and draw an imaginary line from this point to the Zenith. Now, from the observer’s location,
the angle between Zenith→Intersection point on Horizon→Celestial Equator = Latitude of the observer’s location or (90 – number of Latitude degrees observer is away from the North Pole)
the angle between Horizon→Intersection point on Horizon→Celestial Equator = Number of Latitude degrees observer is away from the North Pole or (90 – Latitude of the observer’s location)
Let’s check the results when the observer reaches Kalapokhri (my location at Latitude = 27 degrees North of Equator) on India-Nepal border.
In the Figure 3, it is observed that,
angle between Zenith→Intersection point on Horizon→Celestial Equator = 27 degrees
angle between Horizon→Intersection point on Horizon→Celestial Equator = 90 – 27 = 63 degrees
Wow! This observation for the intersection angle of Celestial Equator at Kalapokhri is as per the theoretical explanation given above.
When he reaches the North Pole, the Celestial Equator will be located along the horizon (90 – 90 = 0 degree). Thus, the entire sky will be in Northern Hemisphere.
This phenomenon is also applicable when we move towards South Pole from Equator. The Celestial Equator will move towards North by 1 degree from Zenith for every 1 degree latitude walk towards South Pole from Equator.
To summarize, for any location on Earth:
The Celestial Equator divides the visible sky anywhere on Earth into Northern and Southern Hemispheres.
The Celestial Equator will intersect the horizon at geographical West and East points. Its angle of intersection relative to Horizon and Zenith will be same for all observers located at the same latitude anywhere on Earth.
All star trails will be parallel to the Celestial Equator.
All stars in the Northern Hemisphere sky (North of Celestial Equator) will form anti-clockwise star trails with the North Star at North Pole as the centre.
All stars in the Southern Hemisphere sky (South of Celestial Equator) will form clockwise star trails with the Polaris Australis at South Pole as the centre.
At the Equator,
star trails in Northern Hemisphere will appear like semi-circles centred around the position at the horizon below which lies the North Star aligned with North Pole.
star trails in Southern Hemisphere will appear like semi-circles centred around the position at the horizon below which lies the Polaris Australis aligned with South Pole.
star trails in the East and West directions will appear perpendicular to the horizon.
At the North Pole, all star trails will appear parallel to the horizon with centre as North Star visible at Zenith of North Pole.
At the South Pole, all star trails will appear parallel to the horizon with centre as Polaris Australis located at Zenith of South Pole.
Today, we have sophisticated technology to understand various cosmic phenomena. However, modern science is built on the work of our ancestors who identified these concepts by meticulous observations and calculations. I bow to them!
Click Celestial Equator for a time lapse video that clearly shows the Celestial Equator with the star trails i.e. Clockwise (in Southern hemisphere – left side of the video directed towards South), Straight (along Celestial Equator) and Anti-clockwise (in Northern hemisphere – right side of the video directed towards North).