Let’s Talk Hemispheric Power (a.k.a. HP)

Let’s Talk Hemispheric Power (a.k.a. HP). This screenshot is from a few days ago and not from today.

Imagine the aurora is a giant cosmic dance party. Hemispheric Power (HP) is how much electricity the DJ has to keep the lights going. More HP = wilder, brighter lights in the sky = better party for us Earthlings.

Who’s measuring this stuff?

Satellites! One called DSCOVR chills 1.5 million km away at a cosmic parking spot called Lagrange Point 1. It’s basically space’s VIP lounge between the Sun and Earth.

Meanwhile, the DMSP satellites stay closer to home and catch particles raining down like glitter. Together, they figure out how wild the party’s getting up top.

If HP drops below 20 GW, chances are slim to none for seeing auroras. But once HP climbs past 50 GW, the aurora party spreads out, lighting up the sky across a much bigger area!

But… Can I See the Aurora Tonight?

If HP is high, auroras go BOOM. But watch out for the Moon — that big spotlight in the sky. She loves to photobomb your aurora pics and drown out the glow. The brighter she is, the more HP you need to compete.

HOW MUCH HP DO YOU NEED TO BEAT THE MOON?

Micro Moon (She’s far away, barely showing off):

0–50% Moon = 50 GW (gigawatt)

50–60% = 60 GW

60–70% = 70 GW

70–80% = 80 GW

80–90% = 90 GW

90–100% = 100 GW

Regular Moon (Just minding her business):

0–30% = 50 GW

30–50% = 55 GW

50–60% = 66 GW

60–70% = 77 GW

70–80% = 88 GW

80–90% = 99 GW

90–100% = 110 GW

Supermoon (Full diva mode, stealing the show):

0–30% = 50 GW

30–50% = 70 GW

50–60% = 84 GW

60–70% = 98 GW

70–80% = 112 GW

80–90% = 126 GW

90–100% = 140 GW — seriously, bring sunnies

Where to Check HP Live:

SpaceWeatherLive App

NOAA Aurora Oval site

So next time you’re planning an aurora chase, don’t just check Kp and Bz — give HP a glance too. It might just save you from freezing under a moonlit sky muttering, “Where is my aurora?!”