That streak in the sky

It's man-made, it's 450 tonnes in weight and yet glides brightly across the sky. The author tells you how you can see the International Space Station from your city

SpotTheStation! Time: Sun Apr 19 8:48 PM, Visible: 1 min, Max Height: 11 degrees, Appears: 11 above N, Disappears 11 above N. Well, the National Aeronautical and Space Administration, more commonly known as NASA, has sent this alert to my email. So tomorrow, April 19, I am going to leave my phone in my room and walk up to the terrace, undisturbed. My eyes will be on my watch to show me 8:48 pm, which is when I will look towards North Delhi from my South Delhi housetop. At 11 degrees there (NASA helpfully informs me that if I stretch out my arm towards the horizon and rest my fist on the horizon, the top of the fist represents approximately 10 degrees), I should see a bright light, visible even over New Delhi's coruscating cityscape. I will have to locate it fast, because the NASA alert says it will be visible only for a minute before disappearing from sight at about the same spot.

I know it is quite some trouble I am going through for one minute of pleasure. But then, what I will be seeing is the International Space Station, the laboratory in the sky, and what is more, I won't even need a telescope to sight it. NASA has a "Spot the Station" programme that alerts people in around 5,000 locations around the world of the day and time when the orbiting spacecraft is visible above that city or town. You can, like I did, go to spotthestation.nasa.gov and register for an alert for the next sighting. You can also find out in advance when it can be seen from wherever you are by entering your location on the website. In April, the ISS can be seen from Delhi on most days of the month, the longest duration of visibility being on April 24 for five minutes.

To understand the message that NASA sends you, look at the horizon chart (above right). The spot at which you can see the largest man-made object in space will be denoted by geographical directions, N, W, S, E for North, West, South and East as well as other points within these cardinal directions. The height from the horizon at which the ISS appears and disappears as well as the maximum height it attains is denoted by degrees. Ninety degrees is directly overhead, so you can approximate any other spot between this and the flat line of the horizon, which is 0/180 degrees.

I am told the space station will look like a star or airplane moving across the sky. The ISS, launched in 1998, travels at an average speed of 27,724 kmph and makes multiple orbits around the Earth every day. It is the third brightest object in the sky after the sun and the moon. However, what you see will depend on the weather; NASA does not consider the sky condition when alerting you to a sighting.

I hope Sunday is cloudless. It would be worth the while to see a streaking mechanical object that weighs 450 tonnes and is as big as a cricket stadium tumbling effortlessly across the night sky.