Here are a few options for a WordPress post tag description, keeping in mind different levels of SEO and detail:

**Option 1: Simple & Concise (Good for general use)**

* **Description:** 無垠宇宙，探索無盡奧秘。 (Endless universe, explore endless mysteries.)

**Option 2: Slightly More Descriptive (Adds context)**

* **Description:** 探索宇宙的奇妙與奧秘。從星系到行星，感受浩瀚無垠的空間與時間。 (Explore the wonders and mysteries of the universe. From galaxies to planets, feel the vastness of space and time.)

**Option 3: Keyword Rich (For SEO – Use with caution: avoid keyword stuffing)**

* **Description:** 宇宙、星空、星系、行星、太空探索、天文學、宇宙學。 包括與宇宙相關的最新新聞、照片、文章和觀點。 (Universe, starry sky, galaxies, planets, space exploration, astronomy, cosmology. Includes the latest news, photos, articles, and viewpoints related to the universe.)

**Option 4: More Focus on Content (Best if you have posts that cover specific aspects.)**

* **Description:** 關於宇宙的所有文章。 涵蓋行星、恒星、星系、宇宙學、太空探索和相關主題。 探索星體的奧秘，了解宇宙之大。 (All articles about the universe. Covering planets, stars, galaxies, cosmology, space exploration and related topics. Explore the mysteries of the celestial bodies, understand the vastness of the universe.)

**Explanation of Choices:**

* **”無垠宇宙” / “浩瀚無垠” / “宇宙的奇妙”:** These phrases capture the vastness and wonder of the universe in a way that is appealing to a Chinese audience.
* **Keywords:** The keyword-rich option includes relevant search terms (星空, 行星, etc.) to help people find your content through search engines.
* **Context:** The other options provide some introductory statements that help the reader understand the purpose of the tag.
* **Tone:** The descriptions are written with a sense of wonder and invite the reader to explore.

**How to Choose:**

* **Your audience:** Consider who you’re writing for. If you’re focusing on a scientific or academic audience, the keyword-rich option might be relevant. If you are focusing on a broader audience, choose a option that is more inviting and inspirational.
* **Your content:** Make sure the description accurately reflects the content that you’re tagging.
* **SEO considerations:** While keywords help, avoid stuffing. Write naturally and focus on providing useful descriptions.

When setting up your tag in WordPress, paste the description into the appropriate “Description” field and try to keep is as short as possible (less than 150-160 characters), so as not to get truncated by search engines. For the perfect description, start with descriptions 2 or 4 and adjust to your liking.