Solar Observing

Solar Sundays are our regular, once-per-month, public solar observing events.

• What: See the Sun safely and up close, like never before!
  • Sunspots
  • Prominences (solar flares)
  • and plenty of Sun science
• Where: Houge Park in San Jose
• When: Usually first Sunday of the Month, in the afternoon
  • Public Event Calendar
  • SJAA on Meetup
• Who: Open to the public and free to attend
• Caution: Do not look directly at the sun without proper protection!

While the night sky certainly offers beautiful sights, we should not neglect our nearest star, the one that gives us light and heat for our days, and provides all the energy that we need to live.

During our Solar Observing events, also known simply as Solar Sundays, we point special telescopes towards our Sun, such that we can see interesting and ever-changing features on its surface and in its atmosphere, features that are otherwise drowned out by its blinding light. (Caution: Do not look at the Sun with unprotected eyes! The Sun will blind you! Only view the Sun through special solar glasses, with appropriate projection systems, or with properly filtered telescopes.)

First, we use strongly filtered white-light telescopes to reveal sunspots. Sunspots exist on the Sun’s photosphere, the closest the Sun has to a surface, and they are regions where strong magnetic fields temporarily suppress heat-transfer from the immense nuclear reactor in the Sun’s core. While they are still really hot and bright, sunspots are cooler and darker than the surrounding areas, and so they appear black to us. Such a sunspot can easily be large enough to encompass the Earth, and when viewed through a telescope, interesting details become apparent in its structure.

Second, we employ Hydrogen Alpha (H-α) telescopes that show us activity in the Sun’s chromosphere, its atmosphere. Here we see prominences and filaments rising from the Sun, consisting of highly energized hydrogen gas, hydrogen plasma, that is shaped by strong magnetic fields. These structures are often huge and colloquially referred to as solar flares, although flares are in fact a different, albeit related, phenomenon.

Our Solar Sunday events are typically on the first Sunday of the Month in Houge Park, near the tennis courts (but always check Meetup for the latest; look for “Solar Observing”). While we’re on Daylight Saving Time, the events run from 2:00 to 4:00 in the afternoon. During the Winter, while the Sun sets earlier, the event window is 1:30 to 3:30 PM. At times we hold special Solar Observing sessions at community events, such as Earth Day or harvest festivals, or we may contribute to educational events (e.g. school or Scout group events) upon request. (For our general, public events, please check our public event calendar or Meetup for specifics.)

Fifteen minutes after the start of a Solar Sunday event, we usually offer an informal, ten-minute intro talk. Other than that, you’ll be able to browse the different telescope stations and speak with the volunteers who are sharing the views of the Sun.

No matter whether Solar Sunday is your first astronomy event, you’ll be able to look through multiple telescopes with your own eyes. The telescope stations may also include real-time sunspot image projections as well as computer video feeds that you can also capture on your smart phones.

And our volunteers will be happy to share more exiting details about our nearest star or tell you about their equipment if you’re curious. All questions are welcome, and you can learn about the Sun’s internal structure, its eleven-year weather cycle, how it affects our lives on Earth, how it relates to other stars, and more.

Beyond telescopes, you may also have a chance to make a solar system you can take home in your pocket or make a bracelet using UV beads that are white indoors but turn myriad colors in sunlight. These activities are especially fun for kids.

Solar Sundays are open to the public and free to attend. You can just show up, although if you RSVP on Meetup, that helps us organize for the day. You may bring and set up your own properly filtered solar telescope (white light or H-α) and share your telescope view with other visitors.

If you enjoy Solar Sunday (or even if you don’t) consider joining SJAA for night-time astronomy as well. (See our public event calendar or Meetup for public events.)

If you like what SJAA offers or simply want to support our mission, consider becoming a contributing member. And we can always use more volunteers to help run Solar Sunday, other events or the administrative side of SJAA. If you’d like to help, don’t worry whether you know enough. We’ll gladly show you the ropes.

As mentioned above, at times we hold special Solar Observing sessions at STEM education-focused events (e.g. school or Scout group events). You may request SJAA to set up solar observing at your event via our request page, and we can work out whether and how we can join you. (Note that SJAA is entirely run  by volunteers who donate their time and expertise as best they can.)

• Current Sun Images
  • NASA Solar Dynamics Observatory (SDO)
  • National Solar Observatory – H-Alpha
• NASA Our Magnetic Sun Poster (original NASA source pdf)
• Crash Course Astronomy by Phil Plait
  • The Sun
  • And other stars:
    • Stars
    • High-Mass Stars
• Solar Astronomy Outreach Companion (Binder used at Solar Sunday Events)
• Paper Tape Solar System Instructions (more printable version)
• UV Bead Supply

This is not an exhaustive list; it is intended as a starting point only.

• Solar Glasses (a.k.a Eclipse Glasses)
  • American Astronomical Society
    • Safe Solar Glasses
    • Solar Glasses Suppliers
• White Light Projection
  • Box Pinhole Projector (NASA hosted video)
  • Build a Solar Funnel (source pdf)
• White Light Solar Filters (for telescopes and binoculars)
  • Objective Filter: Kendrick Astro Instruments
  • Solar Wedge (for refractors; not suitable for reflectors or SCTs)
    • Lunt White Light Solar Wedge
    • Baader Herschel Prism
• Hydrogen Alpha Equipment
  • Lunt Solar Systems
  • Daystar Filters (Quark Eyepiece, etc.)

This is not an exhaustive list; it is intended as a starting point only.

For those who are interested, the following list covers the major pieces of equipment that are owned by SJAA and used during solar observing events. This equipment was paid for by SJAA membership fees (thank you!), donated by private individuals (thank you!) or, in a few cases, donated by corporate sponsors as noted.

Do you want to experience solar astronomy for yourself? For contributing SJAA members, we offer the Loaner Program. Among many other pieces of equipment, the loaner inventory includes two H-α telescopes kits:

• Coronado Personal Solar Telescope (PST)
• Lunt 50

As can be seen below, each of these kits includes the telescope, a double-stacking filter, a set of eyepieces and a few other accessories. (You will need to provide your own mount or borrow that separately from the Loaner Program.)

Note that these H-α telescopes can be tricky to use, and if it’s not done correctly, the Sun will look like an indistinct red blob instead of revealing the desired chromosphere activity. Individuals new to H-α telescopes should plan on attending a Solar Sunday with their newly borrowed telescope to practice the set-up procedure (most specifically the H-α filter tuning step).

• Contact SJAA Solar Program Leadership: Wolf Witt
• Solar Blog

The Sun, January 19, 2025 – White Light, Calcium K, Hydrogen Alpha (by Chris Wood)

Sun Images near 2014 Solar Maximum (by R. Duvall)