Planets visible during Eclipse Aug 21, 2017

Which stars and planets will be visible during the solar eclipse of  August 21, 2017?
North-West of the eclipse will Mars and Venus show up. South-East is Mercurius visible. Just above the eastern horizon will Jupiter be seen. South-East of the eclipse the bright star Regulus can be found.
Information provided for Rexburg (ID).

Hemel - Ciel - Sky

Between July 22nd and September 3th, the Royal Palace in Brussels will host the exposition "Science and Culture" with the theme "Hemel - Ciel - Sky". See also this link.

Have fun !

Venus - Moon Conjunction July 20

Composition made by Guido Gubbels

Some more pictures of the conjunction between the planet Venus and the Moon on July 20 around 12h UT. A summary of the observation is also available on the VVS website.

Moon 11% illuminated - Venus bright NE of the Moon a couple of minutes after conjunction

My picture published in newspaper

My picture of the moon with airplane was published in the national newspaper "Het Nieuwsblad" on July 20th.

One month to go for totallity

Total Sun Eclips in the US.. only one month to go.

Venus in Conjunction with Moon

In total 6 members of Astronomy club Helios gathered together to observe the conjunction between Venus and the Moon. Around 12h UT the moon was about 11% illuminated and Venus was 3° NE of the Moon.

Heliographic Coordinates

In order to define anything on the photosphere of the Sun we need to measure this in terms of heliographic latitude and longitude. This changes by time due to :
1) the fact Earth - Sun distance changes
2) the rotation of the Sun
3) the rotation axis of the Earth being inclined by 23.4° to the ecliptic
4) the rotation axis of the Sun being inclined by 7.25° to the ecliptic

This can be calculated once we have
1) the apparent diameter of the Sun
2) the heliographic latitude B0 of the centre of the Sundisk
3) the heliographic longitude L0 of the centre of the Sundisk
4) the position angle P of the north end of the axis of rotation, when positive it is east of the north point

In a later blog I will post more details about this calculation. Below is the Sun (with Sunspot) including the position angle. The software used was HelioViewer from Peter Meadows.

North is defined by taking two pictures with tracking modus off when using an equatorial set up. By drawing a line between the two sunspots and turning this horinzontal, we find north - south of the Sun.

The "north" positioned Sun (BMP format) is uploaded within HelioViewer. Once your settings (position, time) are entered, the software calculates all coordinates and makes a final drawing of the Sun with Heliographic coordinates.