Do you like graphs and line charts? Astrospheric provides an informative display for North American astronomers to analyse the weather in detail a couple of nights in advance. Additional panels show predictions further out and offer unique line graphs for air temperature, dew point and illumination from the Sun and Moon.
Astrospheric can be viewed through a web browser as well as apps for Android and iOS.
- forecast for eight or more nights
- sky transparency or clarity
- sky seeing or steadiness
- cloud cover
- elevation of Sun and Moon
- air temperature and dew point
- wind speed and direction
- maps for smoke and jet stream
- flyovers for the International Space Station
This program is a relative newcomer to the suite of weather predictive tools for astronomers.
I really like the Astrospheric tool. The top display for the next couple nights is quick and easy to use. The sinusoidal charts for the Sun and Moon are neat. The dew point line graph is extraordinarily helpful.
Reading sky conditions
The website view (above) displays a cloud map for the current time period.
The detailed prediction section shows three rows for cloud cover, transparency and seeing. The coloured-square forecasts are available for a couple of nights, and they can be scrolled left and right. Dark blue is good and white is bad. The data source is the Canadian Meteorological Centre.
Cloud cover and transparency are closely related. No clouds, no haze and no smoke means clear or transparent air, which is good for galaxy and nebula hunting. The seeing information predicts the steadiness or stability of the air. Low scintillation is good for planets, the Moon and double stars.
Astrospheric offers a long-range prognosis extending out 8 to 10 nights (above). This data comes from the Global Forecast System by NOAA. While long-range predictions are less reliable, the Moon and Sun information is useful.
Other weather conditions
The wave-like nature of the Sun (yellow) along with the Moon (grey) rising and setting is illustrated with rhythmic graphs in the short-range and long-range forecasts (above). You can also see specific times are noted. When the curves are synchronised, you’re in a new Moon period — meaning dark skies! The horizontal dashed line indicates the astronomical twilight transition. If you want more details about the Moon, view the bottom of the page. In this section, you’ll also see a little satellite icon from time to time alluding to International Space Station flyovers. Click on it for a sky map with its trajectory.
The wind row (above) indicates direction and speed. If the wind is from the north, Canucks know that means cold temperatures. The speed is hinted at with the colour of the disc where bright blue means windy and dark blue is still.
Air temperature (above) is marked with an orange line while the dew point is bright blue. When they are close or touch, expect dew (or frost) and ready your dew-fighting equipment.
A unique feature is the “Kp” number (above), referring to the predicted Planetary K-index for aurora. A high Kp indicates geomagnetic storms disturbing the Earth’s magnetic field. When it’s higher than 4 or 5, there’s a chance of seeing the Northern Lights from a dark location in Canada.
Checking a time slot
Click on any vertical column in the upper section for details during that hour. The cloud cover map updates. The legend squares for clouds, transparency, seeing, wind, temperature and dew point change.
Below, we clicked on the zero column, after 11 p.m. Wednesday. We can see the Cloud Cover box is dark blue with four-per-cent (thin wispy) clouds. Transparency is bright blue sadly, rated as “Below Average,” and the seeing is no better. It’s a bit breezy at 14 kilometres per hour. The air temperature will be 2 C after midnight, and the dew point should be -4 C. That six-degree gap suggests it won’t be humid or damp. Not great conditions, but after the Moon sets at 10:45 p.m. conditions improve.
Save a spot
Astrospheric lets you save locations. For instance, the top images show a profile for the David Dunlap Observatory in Richmond Hill, Ontario, while the one just above is for St. Mary’s University in Halifax, Nova Scotia, home of the Burke-Gaffney Observatory.
For each favourite location, a coloured bar shows the predicted cloud cover for that site.
Users can store five locations for free. If you have a paid subscription, you can keep an unlimited number of sites.
If you’re really stuck, extensive documentation available at the Help button and a YouTube video describe in detail how to use the product.
The website does not show the barometer nor relative humidity.
Keeping favourite locations in the tool is implemented through a code system. When you provide an email address, a code will be sent to you. If you don’t regularly use the site, you’ll need new codes.
You will notice a play button at the top-right of the map. This should animate the display, but I find this slow and laggy to the point of distraction. I prefer to click a time slot and tap my Left or Right arrow keys.
Using the apps
There is a free mobile app for Android and iOS. It presents the information in the same way as the website and works well in portrait or landscape mode. You can easily switch to your pre-programmed locations using the heart icon.
The mobile app offers a unique “site” mode. Using GPS and network location data from your device, the app displays accurate geomatics data including elevation above sea level. Handy when precisely configuring your telescope mount.
Blake Nancarrow is a double star aficionado, columnist for the RASC Journal, proofreader for the Observer’s Handbook and the interim chair for the RASC Observing Committee. An avid amateur astronomer, he is a member of RASC. Visit his blog at blog.lumpydarkness.com.