What you choose to celebrate, and how, is up to you and your family and friends. Here are some notable days – internationally recognized days, key birthdays relevant to scientific pantheism, and other significant or fun events.  
We can also celebrate the key feasts of our local and national cultures, giving them (when necessary) an earth/human focus.
Colors mark a more selected set. Green – major Earth events. Yellow: Best observance/celebration/reflection

January

1:    New Year’s Day
16: Martin Luther King Day: Anti-discrimination

February

12: Darwin’s birthday: Evolution
14: Valentine’s Day: Day of partners
15: Birthday of Galileo: Solar system
17: Martyrdom of Giordano Bruno: Religious freedom

March

1:  Yellowstone Park established: focus on protected reserves
3: World Wildlife Day
8: International Women’s Day
14: Einstein’s birthday: the Universe
21/22: March equinox
23: World Meteorological Day: Climate & weather

April

1: Fools’ Day – fun and jokes
7: World Health Day: Focus on healthy living
21: John Muir’s birthday — nature reserves 
22: Earth Day
22-28: International Dark sky week

May

1:   Mayday/Beltane: International Workers’ Day
15: International Day of Families 

June

5:   World Environment Day
8:   World Oceans Day
20: World Refugee Day

21/22: Midsummer /Midwinter solstice

July

11: World Population Day 
12: Simplicity Day (Birthday of Thoreau) 
20: Moon landing day (1969)

August

6:   Hiroshima Day – anti-nuclear weapons 
9:   International Indigenous Peoples Day 
12: Perseid meteor shower: Starwatching
26: Krakatoa day: global tectonics.

September

8:   International Literacy Day
15: International Democracy Day
21: International Peace Day
21/22: September equinox

October

2: International Day of Non-Violence (Gandhi’s birthday)
4: World Animal Day
16: World Food Day
31: Halloween

November

2: Day of the dead – remembrance of the dead
13: World Kindness Day: Random Acts of Kindness
16: International Day for Tolerance
23: International Buy Nothing Day
30: John Toland’s birthday (creator of word pantheist)

December

2: International Day for the Abolition of Slavery
10: Geminids peak: Starwatching  
10: Human Rights Day

21: Winter/Summer solstice 
22: International Arbor Day – tree planting
25: Yuletide + Newton’s Birthday