julian weßel - astrophotography


I'm going to travel to the US Solar Eclipse! On 21st August 2017, a lifetime dream comes true, where I will be able to witness one of the most impressive natural phenomena. In addition to that I'll be sending a weather balloon into stratosphere equipped with a camera and a magnetometer. The camera will capture the whole event of totality at an altitude of 30km and you'll be able to see a footage you've never seen before. A Magnetometer will be attached to the capsule below the weather balloon which will detect changes in the Earths Magnetic Field during totality. With these measurements we'll have more data to gain a better understanding of what processes going on within the inner Earth.


As seen from the Earth, a solar eclipse is a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks ("occults") the Sun. A total solar eclipses are rare at any particular location because totality exists only along a narrow path on the Earth's surface traced by the Moon's shadow or umbra.

During a central eclipse, the Moon's umbra moves rapidly from west to east across the Earth. The Earth is also rotating from west to east, at about 28 km/min at the Equator, but as the Moon is moving in the same direction as the Earth's spin at about 61 km/min, the umbra almost always appears to move in a roughly west-east direction across a map of the Earth at the speed of the Moon's orbital velocity minus the Earth's rotational velocity.

The width of the track of a central eclipse varies according to the relative apparent diameters of the Sun and Moon. In the most favourable circumstances, when a total eclipse occurs very close to perigee, the track can be up to 267 km (166 mi) wide and the duration of totality may be over 7 minutes. Outside of the central track, a partial eclipse is seen over a much larger area of the Earth. Typically, the umbra is 100–160 km wide, while the penumbral diameter is in excess of 6400 km.

Interactive Map of the totality Path http://xjubier.free.fr

My chosen location to witness the eclipse and obtain the measurements, is Kansas City. It's south of the path of totality and its easy and convenient to get to by plane from Germany. On August 21st I will drive north to Saint Joseph and start the experiments in this location.

Weather Balloon

To get an introduction into weather balloon flights click here.


To capture the total solar eclipse from high altitude I will be using a weather balloon filled with helium. I get my weather balloons and additional stuff from stratoflights.com. I definitely recommend these guys when purchasing weather balloons and additional stuff. Delivery is always on time and the material is in immaculate condition. The balloon will carry up a payload up to 2kg and is designed to reach an altitude of 35km above the ground. When the balloon reach this altitude the diameter increased from 2m on the ground to 10m at high altitude, This is because the air pressure is much lower at these altitudes and the helium inside the balloon can expand. Once the ballon has reached its maximum stretch capacity, the balloon will bursts and fall back down on earth. The fall is slowed down by a parachute,


The weather balloon is on top and will carry up the payload. The balloon is connected to a parachute which will break the fall from stratosphere. Below that there is a styrofoam box attached, which will carry the camera and the Fluxgate Magnetometer. The camera I will be using is a GoPro Hero 5, which will capture the horizon and a 360° Camera which will capture the ground and the shadow of totality moving across the globe. A GPS Tracker will send information about the balloons location, so it's easier to find the capsule once it has landed.

Magnetometer Measurements

Earth's magnetic field, also known as the geomagnetic field, is the magnetic field that extends from the Earth's interior out into space, where it meets the solar wind, a stream of charged particles emanating from the Sun. Its magnitude at the Earth's surface ranges from 25 to 65 microteslas. The North geomagnetic pole, located near Greenland in the northern hemisphere, is actually the south pole of the Earth's magnetic field, and the South geomagnetic pole is the north pole. Unlike a bar magnet, Earth's magnetic field changes over time because it is generated by a geodynamo (in Earth's case, the motion of molten iron alloys in its outer core).

About 90% of the Earth's magnetic field is generated by this Geodynamo in the Earth's outer core. 10% is generated by solar winds. For this reason, I want to send a Magnetometer into the stratosphere, where it is nearer to the magnetosphere and isn't disturbed by magnetic anomalies, which were caused by human structures. In the measurements we'll see a decrease of the intensity of the Magnetic field during the Solar Eclipse. We want to use this data to get more knowledge of the processes going on in the inner Earth. Because when the sun is blocked by the moon, we only measure the magnetic field which is generated inside of the Earth and we can have a detailed look on it.

For the measurements I'll use a Fluxgate Magnetometer in the weather ballon capsule  and a Cesium Magnetometer as a reference on the ground.

 I'm looking forward to do these experiments and hopefully everything will go well. If you're interested in this project stay tuned. I'll update information about on this website and on my social media.