Monday marks the summer solstice , the first solstice of the year before the winter solstice rolls around in December. Also known as Litha in Pagan and Wiccan traditions, the solstice is widely considered the first day of summer. In fact, it's the longest day of the year. After Monday, our daylight hours will decrease; by the autumn equinox in September, daytime and nighttime will be equal in length.As you might expect, celebrations for the solstice go all day and often pay tribute to the sun. Certain Native American tribes have been known to perform dances and grow trees to better connect the earth to the sun, while Pagan traditions include ritual bonfires (to mimic the warmth of the sun) and feasts. Nowadays, modern-day Pagans honour Litha by meditating on their role in nature and raising awareness for solar energy.The summer solstice signifies the midpoint between the planting and the harvest. May's sensuality has subsided, but a sense of energy and activity remains. Most years, this is enough to make the solstice stand out on the calendar. This year, however, June's full moon, the Strong Sun Moon (according to folkloric traditions), falls on the same day as the solstice for the first time since 1948. To put it another way: This is a very rare — and cosmically advantageous — event.If the name didn't tip you off, the Strong Sun Moon represents the solar activity that permeates the entire month of June. It will rise just as the sun begins to set and remain relatively low in the sky . As with the solstice, you can celebrate this full moon simply by spending time outdoors.Monday is also a good day to take stock of what's present in your life (your relationships, job, and home). It's easy to take these gifts — and the day's extra hours of sunlight — for granted. Instead, make the choice to be especially mindful. The Strong Sun Moon is also saidto encourage spontaneity , and according to the Astrotwins , it happens to be rising in adventurous Sagittarius this year — which means change is most certainly in the air.So, between the solstice, the full moon, and the moon's interaction with Sagittarius, Mother Nature has a lot going on tomorrow. But don't let that overwhelm you — if you can, meditate, call up an old friend, or just observe the energy of the day. If anything, try to take advantage of the extra daylight and catch the sunrise, sunset, and full moon. You can even stream the moon, here , if you can't make it outside.Let us know how you plan to celebrate the summer solstice in the comments, below — and yes, sipping rosé by an open window counts.