Category Archives: Twitter Answers

How Long is the Delay Between DSCOVR and Earth?

Great Question, Thanks Spencer,

The Deep Space Climate Observatory, or DSCOVR, is a satellite launched in 2015 carrying several instruments for measuring space weather. It is stationed about 1.5 millions kilometers from Earth at the gravitational balance point between Earth and the Sun known as Lagrange One. The data from this satellite is available on the space weather prediction center’s website, and it is also used to power the NLN DSCOVR Real Time Solar Wind graphics on this site.

Being 1.5 million kilometers away means there is a lag time between when solar events hit DSCOVR and when they arrive at Earth. Clouds of charged particles that travel on the solar wind, such as CMEs and solar storms, typically travel at between 350 and 800 km/s. At those speeds, it takes between 30 and 75 minutes for events measured at DSCOVR to arrive at Earth. When the solar wind is moving faster, like during a coronal hole high speed wind stream or while Coronal Mass Ejection solar storm is passing, the lag time is less. When wind speeds are more ambient, the lag time is longer. Here’s a helpful chart to help see the relationship between wind speed and lag between DSCOVR and Earth:

This table shows the lag between data is measured at DSCOVR and when it registers at Earth
This table shows the lag between data is measured at DSCOVR and when it registers at Earth

There is currently no way of measuring the orientation of the magnetic fields of clouds traveling on the solar wind until they reach DSCOVR. Space weather forecasters are dependent on the measurements taken at the satellite to seed the models that predict aurora. This is why accurate KP predictions can only be made 30-75 minutes in advance. In addition to letting aurora hunters on Earth know what to expect, the data also provides lead time to near earth satellite operators to know if they need to put their satellites in hibernation or protective modes to shield from magnetic fields that could damage sensitive electronics on board.

Fun Fact – DSCOVR also hosts the EPIC (Earth Polychromatic Imaging Camera) instrument, famously championed by Al Gore. This camera beams a true-color image of Earth about once every two hours. You can see the images it is sending back by following the EPIC twitter account. Read about all the specs of the camera on board here.

"Blue Marble" style image of Earth from EPIC camera on October 17,  2016
“Blue Marble” style image of Earth from EPIC camera on October 17, 2016

Happy Hunting

Are the Aurora and Northern Lights Active Now?

Thanks for this question Parin,

Your best bet for determining if there is currently aurora activity is to take a peak at the current KP value. The chart on that page shows the current KP and the expected KP over the next 30-75 minutes. KP is a global scale that ranges from 0 to 9, the higher the value, the more active the aurora is and the closer to the equator it may be visible.

Once you know the current KP, you will want to know if it is possible to see aurora where you are at that KP. This map helps with that:

Global KP boundaries map shows what KP you need to see Aurora
Global KP boundaries map shows what KP you need to see Aurora[/

[caption id="attachment_1365" align="aligncenter" width="689"]Southern Hemisphere KP Maps Southern Hemisphere KP Maps

Find your location on this map, If you are in the Northern Hemisphere the KP level you need is the line to the south of your location. Likewise, if you are in the southern hemisphere the value you need is on the line to the north of your location.

Finally, check your weather. Aurora displays are high in the atmosphere. If it is cloudy, the aurora will be above the clouds and you will not be able to see them.

Happy Hunting

Scandinavian Northern Lights in October

This afternoon Burcu Basar (@BurcuBasarBlog) asked a question on Twitter:

Great question! We hear it often. The answer needs to be more than 140 characters.

The short answer is yes. There are a number of reasons Norway, Sweeden and Finland are terrific travel location for aurora hunters. But surprisingly, this has nothing to do with there aurora activity in October – it comes down to it being the right balance of warm (or at least not insanely cold) and dark.

The longer answer:

Solar storms arrive at Earth in a pattern governed by activity cycles on the Sun which are completely independent of the position of Earth or the season on Earth. Solar storms and aurora are just as likely to happen in October as in any other month.

The solar cycle can be used for determining how likely it is that your visit to a higher latitude location will coincide with an aurora show. This 11-year cycle governs the number of active regions and sunspots on the sun. Generally speaking, when there are more sunspots, solar storms from flares are more likely and aurora are more likely. So, a trip to Scandinavia during the peak of the solar cycle is more likely to reward an aurora hunter. The current solar cycle, “cycle 24”, is now in it’s declining phase, but there are still plenty of nights with aurora in store over the next several years. Here’s a graph showing the progress of the current solar cycle:

Graph of Solar Cycle 24
Solar Cycle Progression as of Sept 2015

Because a solar storm can arrive any time of the year, and at any time of day, the best place to be is where it is dark for a larger percent of the day. In the northern hemisphere, this means September through March, in the southern hemisphere March through September are the best aurora hunting months.

It also has to be clear to see the aurora because they are above the clouds. So, once you’ve picked a place to visit, choose a time of year where it is more likely to be clear skies.

In Vermont, where NLN is based, we frequently hear that August is the best time of year for northern lights – which goes entirely counter to the previous paragraphs. This discrepancy is due to weather. In August is it summer, its is warm and people are camping. People spend more time outside at night, and see more aurora. In the winter it’s cold and people huddle by their fireplaces at night, so they don’t even notice the aurora going on just outside their door. This leads to a perception that summer is a better time of year to see aurora.

Autumn seems to be the most comfortable and rewarding time of year to hunt aurora. The nights get longer, and the temperature hasn’t dropped too much yet.

So yes – go visit Scandinavia during October. Even if you don’t see the lights, it’s a wonderful place to visit.

Happy Hunting