Category Archives: Solar Science

Video: The dance of the Earth and Moon as seen by DSCOVR

NOAA’s DSCOVR (Deep Space Climate Observatory) spacecraft  has a clear view of the hemisphere of the Earth facing the Sun. This can give it a great view of the Moon and Earth together. In the video below, I concantenated three videos produced by the EPIC (Earth Polychromatic Camera)  on DSCOVR, two of which show the Moon crossing the face of the Earth and one showing the Earth eclipsing the Moon.

The reason that the DSCOVR spacecraft can obtain such views is because it sits a million miles away from Earth on the L1 Lagrange point (see diagram below). L1 is one of five Lagrange spots where an object can remain fixed relative to the earth due to the counterbalancing pulls of the Sun and Earth’s gravitational forces and the inertia of the object.

l1_DSCOVR_diagram[1]Diagram of DSCOVR  at the L1 point. (Credits NOAA).

Here is a new video that shows a time lapse of one year of DSCOVR images of Earth:

The Sun flips in Solar Dynamics Observatory imagery

Here’s a cool GIF animation of images of the sun from the Solar Dynamics Observatory (SDO):

Sun-Watching SDO Does a Somersault

On July 6, 2016, engineers instructed NASA’s Solar Dynamics Observatory, or SDO, to roll 360 degrees on one axis. SDO dutifully performed the seven-hour maneuver, while producing some dizzying data: For this period of time, SDO images – taken every 12 seconds – appeared to show the sun spinning, as if stuck on a pinwheel. This video was taken by SDO’s Atmospheric Imaging Assembly instrument in extreme ultraviolet wavelengths that are typically invisible to our eyes, but was colorized here in gold for easy viewing.


This maneuver happens twice a year to help SDO’s Helioseismic and Magnetic Imager, or HMI, instrument take precise measurements of the solar limb, the outer edge of the sun as seen by SDO. Were the sun perfectly spherical, this would be a much simpler task. But the solar surface is dynamic, leading to occasional distortions. This makes it hard for HMI to find the sun’s edge when it’s perfectly still. HMI’s biannual roll lets each part of the camera look at the entire perimeter of the sun, helping it map the sun’s shape much more precisely.

HMI tracks variations in the solar limb over time to help us understand how the shape of the sun changes with respect to the solar cycle, the sun’s 11-year pattern of solar activity. The more we know about what drives this activity – activity that can include giant eruptions of solar material and radiation that can create hazards for satellites and astronauts – the better we may someday predict its onset.

The Sun goes spotless as it falls towards a Minimum

The Sun has gone spotless as it enters the less active phase of the solar cycle: Vanishing Sunspots – – June.4.2016 –

Forecasters expect the next Solar Minimum to arrive in 2019-2020. Between now and then, there will be lots of spotless suns. At first, the blank stretches will be measured in days; later in weeks and months. Don’t expect space weather to grow quiet, however. Solar Minimum brings many interesting changes. For instance, as the extreme ultraviolet output of the sun decreases, the upper atmosphere of Earth cools and collapses. This allows space junk to accumulate around our planet. Also, the heliosphere shrinks, bringing interstellar space closer to Earth. Galactic cosmic rays penetrate the inner solar system with relative ease. Indeed, a cosmic ray surge is already underway. Goodbye sunspots, hello deep-space radiation!


The average number of sunspots has been dropping steadily for months:

ISES Solar Cycle Sunspot Number Progression - NOAA

Watch the changing Sun on the HobbySpace Sun & Space Weather page.

Videos: Solar observatory spacecraft captures great views of Mercury transit

The Mercury transit was seen by observers on the ground and by satellites in space. The best views of the transit came from the Solar Dynamics Observatory (SDO) spacecraft, whose multiple imagers showed the transit in different parts of the spectrum:

Another SDO view:

Here is a NASA panel discussion about the transit:

Mercury to transit the Sun on Monday

On Monday the planet Mercury will transit across the face of the Sun as seen from earth between about 7:12 am  and 2:42 pm EDT : Mercury Enters Spotlight on May 9 – NASA.

This video shows the path that it will take:

Don’t ever look directly at the sun. There are various safe ways to observe the transit such as using a solar filter over a telescope aperature or to project the image onto a white board with a pinhole. The transit will also be webcast from various sites.

Here are some sites with information on webcasts and tips on viewing the transit directly: