## Students Measure Distance to Comet Hyakutake

Below is an abbreviated version of a detailed report , just published on the Web pages of the Soenderborg Gymnasium in Denmark. It concerns a unique, international student project, successfully organised under the auspices of the European Association for Astronomy Education (EAAE).

### Students measure Parallax; Distance and Speed of Comet Hyakutake

The following picture illustrates what is probably the first amateur + school based effort to estimate the distance to a comet, by means of the parallax method.

Simultaneous Pictures of Hyakutake, obtained on March 22, 1996.

Pupils and teachers at a number of EAAE-connected schools in Sweden, Denmark, Germany and Spain have eagerly tried to photograph the comet Hyakutake in close co-operation with the active members of the Associacao Portuguesa de Astronomos Amadores - in Lisbon (email: antonio.alves@telepac.pt.)

March is usually a month with bad weather, and following one of the hardest winter in 10 years, this was also the case during the March 1996 approach of Comet Huyakutake.

However, during the night of March 22, clear skies finally appeared over two of the involved EU countries, Portugal and Denmark.

The picture above shows simultaneous photos of this comet (the elongated image) while it was passing close to the bright star SAO 101241.

Denmark is placed higher on the globe compared to Portugal.

This is equivalent to the situation where you climb the roof of your house: seen from 'above', all neighbouring objects will appear lower compared to your normal horizon.

The method applied to determine the parallax and thereby the distance to comet Hyakutake is a classical mathematical/astronomical exercise. We use both a simplified 2D- and a comprehensive 3D-method.

Simplified Drawing, 2D, Earth Globe + Comet.

The line of sight for a Danish observer is different from that of a Portuguese observer; the 'parallax angle' is the angle between the two directions. The closer the comet, the larger is this angle. Thus, a measurement of the parallax immediately gives the distance to the comet.

Parallax Angle, Denmark-Comet-Portugal.

So far, our best results are obtained using:

Simple 2D approach: comet distance = 13 million km.
Full 3D Math: comet distance : 17-18 million km.
Actual comet distance: 22 million km.

Please note that this is part of an EAAE / APAA Joint Student project - and all data are still very preliminary!