The International Space Station hap­pened to be pass­ing by when I was out doing some astropho­tog­ra­phy. It’s a very high-profile object because it’s a lot brighter than any stars (it’s light com­ing from the solar pan­els reflect­ing the sun at us), and it blazes across the sky at an amaz­ing speed. This last point is made obvi­ous by the fact that all the stars appear sta­tion­ary in the photo1, while the ISS made a bril­liant streak.

Also vis­i­ble near the bot­tom of the pic­ture are two low-flying air­craft. The one in the bot­tom left cor­ner had blink­ing lights, which is why it appears as a series of dots in a line.

International Space Station

16mm focal length, f2.8 aper­ture, 13 sec­ond expo­sure, ISO1600.

I only had about two chances to take this shot at this shut­ter speed, not because the ISS dis­ap­pears behind the hori­zon, but because it even­tu­ally flies into the shadow of the Earth while it’s in the sky and is no longer illu­mi­nated by the sun.

My astropho­tograhy teacher once showed me a pic­ture he got of the ISS where the fins of the solar pan­els were vis­i­ble. To put into per­spec­tive how dif­fi­cult this was, he explained it like this:

At it’s longest dimen­sion, the ISS is only about 109m wide, which is roughly the size of the nee­dle antenna on top of the CN Tower. It’s also orbits about 400 kilo­me­tres above the earth, which is roughly the dis­tance from Ottawa to Toronto. So to cap­ture the ISS in a tele­scope at that mag­ni­fi­ca­tion is like being in Ottawa and point­ing a tele­scope at Toronto and see­ing the antenna on the CN Tower…as it’s mov­ing at 8 kilo­me­tres per sec­ond. In American terms, this would be like stand­ing with a tele­scope in Las Vegas and resolv­ing the char­ac­ters of the Hollywood sign in Los Angeles if it was mov­ing at 17000mph.

  1. They do move, but at a wide focal length of 16mm the streak­ing is min­i­mized. [↑]