Question: a single period of precession of earth's axis is completed in about
[{'answer': '26,000 years', 'provenance': [{'wikipedia_id': '72576', 'title': 'Axial precession', 'start_paragraph_id': 11, 'start_character': 240, 'end_paragraph_id': 11, 'end_character': 252, 'bleu_score': 1.0, 'section': 'Section::::Effects.\n'}]}, {'answer': 'approximately 26,000 years', 'provenance': [{'wikipedia_id': '72576', 'title': 'Axial precession', 'start_paragraph_id': 11, 'start_character': 226, 'end_paragraph_id': 11, 'end_character': 252, 'bleu_score': 1.0, 'section': 'Section::::Effects.\n'}]}, {'provenance': [{'wikipedia_id': '72576', 'title': 'Axial precession', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 582, 'bleu_score': 0.806207014367146, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3062435997306232445}, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '72576', 'title': 'Axial precession', 'section': 'Section::::Effects.\n', 'start_paragraph_id': 11, 'end_paragraph_id': 11, 'meta': {'evidence_span': ["The precession of the Earth's axis has a number of observable effects. First, the positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in approximately 26,000 years.", "The precession of the Earth's axis has a number of observable effects. First, the positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in approximately 26,000 years", "The precession of the Earth's axis has a number of observable effects. First, the positions of the south and north celestial poles appear to move in circles against the space-fixed backdrop of stars, completing one circuit in approximately 26,000 years."]}}]}]