It is that knowledge of Astro-Navigation helped the rescue of a lost small Cessna-188 aircraft in the South Pacific Ocean. Some readers may remember the original incident involving Air New Zealand flight NZ103 from 21 Dec 1978 [Wikipedia] or perhaps may have seen a slightly modified TV movie "Mercy Mission: The rescue of flight 771" from 1992 [TV]. The movie used a B767 instead of a DC-10, and called the flight 803 instead of 103, but the story is similar.

Essentially, the story starts off with a small Cessna agricultural crop-dusting aircraft lost over the South Pacific with a malfunctioning navigational ADF. It was being ferried via selected islands from the USA to Australia, many years before operational GPS. While en-route, the pilot didn't make his anticipated landfall and realized that his position was in doubt. Using an HF radio, Auckland Air Traffic Control decided that the only other aircraft nearby was an Air New Zealand DC-10. That crew, with the passenger's approval, decided to search for him. They managed to narrow in on an approximate position with the sun using basic celestial navigation "Astro Nav" principles. They also used VHF radio range knowledge to refine the location further. Ultimately they didn't make a visual observation of the aircraft, but their information and VHF radio communications assisted in the overall rescue effort. It was also later proven that their calculated position estimates were accurate. Eventually the Cessna spotted the lights of a towed sea platform and was then able to establish its precise location. It ended up landing safely on Norfolk Island [map] with minimal fuel after a lone 23 hour and 5 minute flight!

The Astro Nav part involved both aircraft aiming straight for the Sun and getting an accurate bearing towards it. The DC-10 had a bearing of 270 ºM and the Cessna 274 ºM. They also used extended arms and fingers to help estimate the vertical height of the low sun to the horizon. The DC-10 had an angle of 4º and the Cessna had an observed angular height of  8º degrees. Later, the exact time of locally observed sunset was recorded as well from both the Cessna and the destination airfield. From all this information it could be obtained that: With a 4º difference in sun bearing, the Cessna was further South then the DC-10. Additionally the 4º difference of vertical sun angle meant that the Cessna was approximately 4º further West, or about 240Nm. This approximation to the southwest allowed the DC-10 to fly within VHF radio range (r=200Nm) within a matter of minutes. The tropical air prevented a natural contrail on this occasion and an attempt to be seen by making an artificial fuel-dumping trail also proved unsuccessful. Lastly, comparing sunset times confirmed that the Cessna was 5.5º longitude east of Norfolk Island, the destination airport. In the end, all estimates were considered accurate and helpful. More... [More info]

Watching the International Space Station ISS pass overhead in twilight is always an inspiration and we recommend ways to see it on our Space page [Space]. In the Northern Hemisphere, satellite viewing is very opportunistic due to the extra twilight provided by the of midnight sun.

NASA's "Curiosity" rover [NASA] is heading to Mars with a landing date this summer on 6 August. It will also be fascinating to watch private company SpaceX rendezvous its Dragon (COTS2) spacecraft with the ISS, most recently rescheduled for late May [SpaceX]. Incidentally, Virgin Galactic's SpaceShipTwo will be inching much closer in 2012 [Space] with powered tests expected to be carried out in this year and passenger possibly 2013. The Chinese [BBC] also practiced a rendezvous in 2011 with their Tiangong-1 [wiki] Space Laboratory and unmanned Shenzhou-8 [wiki], in preparation to their 4th manned mission, perhaps in June this year, Shenxhou-9 [wiki]. Of interest, the North Koreans failed in their attempt to join the space race in April [BBC-Failed], [pre].

In Spring from more northerly latitudes, evening dusk favors the Zodiacal Light [Atmosphere]. But note that from the tropics, any time of year is good to see it at dusk or dawn.

In Spring the geometry for evening twilight planets [Planets] in the mid Northern Hemisphere is best. Morning planets will be poor or  maybe impossible in the extreme far north. Nevertheless super-bright Venus should be brightly visible in evening twilight until late May when it rapidly descends to swing past the Sun during its historic Venus Transit June 5/6 [NASA], [wiki]. It will then rapidly rise in the morning sky throughout June and remain there all summer. It is very bright and white in color unless it is setting on the horizon. Take the time to watch it set from altitude when airborne because it can flicker very intensely. It may at times seem like aircraft lights or a pulsing red flare. Throughout May and June, Venus will be a large crescent which is detectable through stable binoculars! BEWARE: Never look at the Sun.

Bright Jupiter is no where to be seen because it is too close to the sun. It will emerge in the morning sky by mid-June and stay just above Venus. Although Venus is brighter, as recently as Autumn 2011 when Jupiter was at opposition, a Lifeboat and an RAF Helicopter were sent out to investigate an emergency flare [BBC], that ended up being simply Jupiter flickering in the sky. The illusion is quite real. A warning to pilots that some bright planets can be confused with approaching landing lights when you are unsuspecting!

Visible in the west as it gets dark in the evening is bright reddish Mars. Dimmer Saturn is above, and always ready to show you its rings through any telescope!

Mercury is pops up in the evening sky in May. 

May starts with the Eta Aquarids Meteor Shower that peaked s on 6 May [Meteors], but remember that there could randomly be a great meteor at any time! For example, NASA is still looking for witnesses [NASA] to the Meteor of 22 April 2012. It was heard from below when it blew-up and pieces were found in central California.

Better weather down route in many regions means its  time to go exploring Observatories, Museums or Planetariums. Please see our list of activities and consider contributing one yourself [Down Route].

Noctilucent Cloud [Atmosphere] season does not start (in the Northern Hemisphere) until late May. However there may always be something unknown to witness. Lower, but rarer, high Arctic Nacreous Clouds season is finished until Winter in the northern hemisphere.

Of all the Eclipses this year, the most significant is a Transit of the planet Venus in front of the Sun on June 5th or 6th depending on where you are on the world. Nobody witnessing this event, old enough to fly a plane, will be alive to see the next one, so please treat it with respect. Otherwise, there is one Annular Eclipse May 20-21st [Sun] spreading from near Hong Kong to Tokyo to the North Pacific and back down to northern California, one Partial Lunar Eclipse [Moon] that will be seen by most people on the Pacific Ocean side of the world. A Total Solar Eclipse in the South Pacific that most people won't see, and a Penumbral Lunar Eclipse that most people wouldn't even notice.

Happy Discoveries!