What's that bright light in the night sky?

Below are descriptions of some of the bright moving objects you might encounter in the night sky. Record the time you saw an object and the hyperlinks below will take you to records on the wonderful Heavens-above website of when the identified object should have passed over and when it is likely to be seen again (click on Next and Prev to check other dates when you are on the Heavens-above website).

Is the body you are observing...
..Slow Moving
- Satellites
- Int. Space Station
- Space Shuttle
(click here)
..Fast Moving
- Meteors
- Fireballs
(click here)

 

Slow moving bodies

Normal satellites - Watch the night sky for enough time and you'll be able to see a tiny spot of light slowly track across the sky. These are rarely much brighter than an average star. These are satellites, and can be as little as much as ~40,000 km above the Earth for the TV, telephone and data satellites!! These track at a constant rate and light intensity for a long distance, and may take a minute or so to cross the entire sky.

International Space Station - The International Space Station can be seen from Earth when its large solar panels reflect the sun back to earth at night. It's more than 334-348 km above your head! When will it next pass visibly over Fredericton? Find out here. The Space shuttle also travels at about 300 km above the Earth's surface when it is in orbit, unless it is going to meet the Space Station.

Iridium Satellites - The Iridium satellites are a set of communication satellites used for global satellite phones. They have large solar panels that can reflect the sun back down to earth at night when they are in just the right orientation. These appear as slow moving points of light that get gradually brighter and then dimmer. They move slower than meteors and fireballs and tend to have short tracks.

Fast moving bodies

Meteors - Meteors are produced when grains of sand-sized material burns up in our atmosphere. This material includes rocky dust particles and cometary debris. A meteor shower occurs when the Earth's orbit takes it through the debris left behind from the passage of an ancient comet. This is why meteor showers tend to occur at certain times of the year: at those times of year the Earth passes through the same trail of comet junk.

2007 looks to be a good one for meteor-watching because bright moonlight will not interfere with most of the better, more-dependable displays. Here are the dates and estimated hourly rates of some of the major showers:

2007 Meteor Showers
Shower
Radiant and
direction

Morning of
maximum

Hourly rate
Quadrantid*
Draco (NE)
Jan. 4
40
Lyrid
Lyra (E)
Apr. 22
10-20
Eta Aquarid*
Aquarius (E)
May 6
20
Delta Aquarid
Aquarius (S)
July 28
20
Perseus (NE)
Aug. 13
60
Orionid
Orion (SE)
Oct. 22
10-15

Leonid

Leo (E)
Nov. 18
10
Geminid
Gemini (S)
Dec. 14
75
* Moonlight will wash out fainter meteors in these showers.

 

Fireballs - Fireballs are bright meteors. The distinction between a meteor and fireball is somewhat arbitrary - though fireballs are always generated by larger chunks of rock (meteoroids) passing through the atmopshere. These are significant, because they may make it all the way through their fiery passage in the atmosphere and make it to the ground, where they are called meteorites.

Fireballs often change in brightness and can become very bright as fragments break off or when the meteoroid actually breaks into pieces. This can occasionally be accompanied by sound, as the shock wave generated by the break-up passes through the atmosphere and reaches the ground. The sound will always occur after the bright flash because sound travels slower to the ground than does the light from the flash. The delay can be used to define how far away the fireball actually is from the observer, in a similar way that the delay between seeing lightening and hearing thunder can define the distance to a storm.

You won't find fireballs on the Heavens-above website because they don't occur at predictable times - it all depends on when random pieces of meteoroid enter the atmopshere.

What does the night sky look like today over Fredericton? Find out here

 

Links

General Observation websites

New Brunswick Astronomy Groups