NGC 1952 - Messier 1 - The Crab Nebula
The outward arrows indicate how much
larger the Crab Nebula will be in 250 yrs.
The Crab Nebula is one of the most famous known objects in the sky. Nearly every astronomy textbook has a photo and describes it. This is what the Crab Nebula looks like today. It is the remnant of a supernova explosion witnessed by Chinese astronomers on the morning of July 4, 1054. The Chinese reported the new object ("guest star") to be so bright, that it was visible in daylight for 22 days. Its current size measures 4 x 6 light years and continues to expand at the rate of over 2,000 kilometers per second. (2,000 km = size of Texas !!). The outward arrows indicate how much larger the Crab Nebula will be in 250 years.
Read about the Crab Nebula's expansion here and here
The International Occultation Timing Association (IOTA)
The International Occultation Timing Association consists of professional and amateur astronomers dedicated to the study of specialized eclipses by the Moon, asteroids and other solar system objects. IOTA provides detailed predictions these "occultation" events, including total lunar occultations, grazing occultations, asteroid occultations, occultations of planetary satellites, plussolar and lunar eclipses. IOTA not only provides the predictions, but promotes the observations and data reduction of these scientifically valuable events.
IOTA activities include:
Popular and Technical IOTA References and Articles 1964-Present
Highlights of IOTA's Annual meetings: Annual Meetings Summary and History Page
Introduction to Occultations - 11 page tutorial - A must read for all occultation observers novice or expert
Free e-book on occultations: Chasing the Shadow: The IOTA Occultation Observer's Guide This is IOTA's complete guide to observing lunar, grazing and asteroid occultations plus solar eclipses
Also see the 11-page Introduction to Occultations
Double Stars Richard’s Bio .. Artificial Occultations .. Richard’s Unusual Target .. Venus Occultation
Moon’s eliptical orbit .. Questar Platform ....... GPS VTI Comparison ......Photo Gallery ......Stellar Motions
Lunar Eclipse 10-27-2004 ...Derail the Astronomical League ......Questar low latitude platform .....GPS VTI Comparison
Artificial Occultations ....Solar Eclipses Aug 21 2008 Eclipse .....Jan 15 2010 Eclipse ....Jul 11 2010 Eclipse