Feeds

How far can the naked eye see?

Star gazing

High performance access to file storage

Also in this week's column:

How far can the naked eye see?

The human eye can see an almost unlimited distance. Looking up into the sky on a very clear night, the Triangulum Galaxy can sometimes be seen. This is a distance of 3.14 million light years. The Andromeda Galaxy is also sometimes visible. This is a distance of 2.5 million light years.

However, it must be pointed out that when we see these galaxies what we actually "see" is something at a somewhat lesser distance. What we "see" is light from the far away object rather than the object itself. What happens is that light coming from the object strikes our optic nerve. The optic nerve signals the brain. The brain then interprets this message and forms an image. The brighter the object, the farther away it can be from us and still be "seen".

The star, Rigel, is many times brighter than another star, Alpha Centauri, yet Alpha Centauri is many times closer.

According to Dr Brent Archinal of the Astrogeology Team of the US Geological Survey in Flagstaff, Arizona writing in the May, 1997 issue of Astronomy, the human eye can see about 2,500 stars in the clearest of night skies. But usually only about 1,500 to 2,000 stars can be seen due to weather, pollution, etc, and fewer still in night skies of cities due to the additional factor of city lights.

Five planets can be seen from earth with the naked eye under the best of circumstances: Mercury, Venus, Mars, Jupiter, and Saturn.

Stephen Juan, Ph.D. is an anthropologist at the University of Sydney. Email your Odd Body questions to s.juan@edfac.usyd.edu.au

High performance access to file storage

More from The Register

next story
Fancy joining Reg hack on quid-a-day challenge?
Recruiting now for charity starvation diet
Red-faced LOHAN team 'fesses up in blown SPEARS fuse fiasco
Standing in the corner, big pointy 'D' hats
KILLER SPONGES menacing California coastline
Surfers are safe, crustaceans less so
LOHAN's Punch and Judy show relaunches Thursday
Weather looking good for second pop at test flights
Discovery time for 200m WONDER MATERIALS shaved from 4 MILLENNIA... to 4 years
Alloy, Alloy: Boffins in speed-classification breakthrough
Elon Musk's LEAKY THRUSTER gas stalls Space Station supply run
Helium seeps from Falcon 9 first stage, delays new legs for NASA robonaut
Top Secret US payload launched into space successfully
Clandestine NRO spacecraft sets off on its unknown mission
New FEMTO-MOON sighted BIRTHING from Saturn's RING
Icy 'Peggy' looks to be leaving the outer rings
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.